The NRG Astrodome, also known as the Houston Astrodome or simply The Astrodome, is the world's first multi-purpose, domed sports stadium, located in Houston, Texas. Construction on the stadium began in 1962, and it officially opened in 1965. It served as home to the Houston Astros of Major League Baseball (MLB) from its opening in 1965 until 1999, and the home to the Houston Oilers of the National Football League (NFL) from 1968 until 1996, and also the part-time home of the Houston Rockets of the National Basketball Association (NBA) from 1971 until 1975. Additionally, the Astrodome was the primary venue of the Houston Livestock Show and Rodeo from 1966 until 2002. When opened, it was named the Harris County Domed Stadium and was nicknamed the "Eighth Wonder of the World".
After the original natural grass playing surface died, the Astrodome became the first major sports venue to install artificial turf, which became known as AstroTurf. In another technological first, the Astrodome featured the "Astrolite", which was the first animated scoreboard. The Astrodome was renovated in 1988, expanding seating and altering many original features.
By the 1990s, the Astrodome was becoming obsolete. Unable to secure a new stadium, Oilers owner Bud Adams moved the team to Tennessee after the 1996 season, where they eventually became the Tennessee Titans. The Astros played at the dome through the 1999 season, before relocating to Enron Field (later changed to Minute Maid Park) in 2000, while the Houston Livestock Show and Rodeo continued to be held at the Astrodome until the opening of the adjacent NRG Stadium in 2002. Although it no longer had any primary tenants, the venue regularly hosted events during the 2000s, and in 2005, was used as a shelter for residents of New Orleans affected by Hurricane Katrina. The Astrodome was declared non-compliant with fire code by the Houston Fire Department in 2008 and parts of it were demolished in 2013 after several years of disuse. In 2014 it was listed on the National Register of Historic Places. In 2017, the Texas Historical Commission designated the Astrodome a State Antiquities Landmark.
Video Astrodome
History
Conception
Major League Baseball expanded to Houston in 1960 when the National League agreed to add two teams. The Houston Colt .45s (renamed the Astros in 1965) were to begin play in 1962, along with their expansion brethren New York Mets. Roy Hofheinz, a former mayor of Houston, and his group were granted the franchise after they promised to build a covered stadium. It was thought a covered stadium was a must for a major league team to be viable in Houston due to the area's subtropical climate and hot summers. Game-time temperatures are usually above 97 °F (36 °C) in July and August, with high humidity and a likelihood of rain. Hofheinz claimed inspiration for what became the Astrodome when he was on a tour of Rome, where he learned that the builders of the ancient Colosseum installed giant velaria to shield spectators from the Roman sun.
The Astrodome was conceived by Hofheinz as early as 1952, when he and his daughter Dede were rained out once too often at Buffalo Stadium, home of Houston's minor league baseball team, the Houston Buffs. Hofheinz abandoned his interest in the world's first air-conditioned shopping mall, The Galleria, and set his sights on bringing major league baseball to Houston.
Design and construction
The Astrodome was designed by architects Hermon Lloyd & W. B. Morgan, and Wilson, Morris, Crain and Anderson (Morris Architects). Structural engineering and structural design was performed by Walter P Moore Engineers and Consultants of Houston. It was constructed by H. A. Lott, Inc. for Harris County, Texas. It stands 18 stories tall, covering 9.5 acres (3.8 ha). The dome is 710 feet (220 m) in diameter and the ceiling is 208 feet (63 m) above the playing surface, which itself sits 25 feet (7.6 m) below street level.
The scoreboard, eventually known as the "Astrolite", was designed by Fair Play Scoreboards of Des Moines, Iowa. Having designed the scoreboard for Dodger Stadium several years prior, team owner Roy Hofheinz was not impressed with the initial proposal for a much more generic type of scoreboard. Project designer Jack Foster teamed up with a creative professional based in Kansas City to create the first animated scoreboard. Its reported cost was $2.1 million.
The Dome was completed in November 1964, six months ahead of schedule. Many engineering changes were required during construction, including the modest flattening of the supposed "hemispherical roof" to cope with environmentally induced structural deformation and the use of a new paving process called "lime stabilization" to cope with changes in the chemistry of the soil. The air conditioning system was designed by Houston mechanical engineers Israel A. Naman and Jack Boyd Buckley of I. A. Naman + Associates.
The multi-purpose stadium, designed to facilitate both football and baseball, is nearly circular and uses movable lower seating areas. It also ushered in the era of other fully domed stadiums, such as the Pontiac Silverdome near Detroit and the Mercedes-Benz Superdome in New Orleans, as well as the now-demolished Hubert H. Humphrey Metrodome in Minneapolis, Kingdome in Seattle, and RCA Dome in Indianapolis.
To test what effect the enclosed air-conditioned environment might have on the delivery of breaking balls, Satchel Paige, in full Astros uniform, threw the first pitches at the Astrodome on February 7, 1965. He later concluded that it was a "pitcher's paradise", as the lack of wind allowed for sensitive pitches to maneuver more easily.
Hofheinz had an opulent apartment in the Dome, which was removed when the facility was remodeled in 1988.
Opening and reception
On Opening Day, April 9, 1965, a sold-out crowd of 47,879 watched an exhibition game between the Houston Astros and the New York Yankees. President Lyndon B. Johnson and his wife Lady Bird were in attendance, as well as Texas Governor John Connally and Houston Mayor Louie Welch. Governor Connally tossed out the first ball for the first game ever played indoors. Dick "Turk" Farrell of the Astros threw the first pitch. Mickey Mantle had both the first hit (a single) and the first home run in the Astrodome. The Astros beat the Yankees that night, 2-1.
President Johnson stopped at the Astrodome that evening en route to his home in Johnson City and paid his respects to baseball and Astros president Roy Hofheinz, a campaign manager for Johnson in the 1940s, just as the second inning got underway. He and Lady Bird watched the opening night game from behind the glass in Judge Hofheinz' private box high in right field just to the right of the giant scoreboard. LBJ ate hors d'oeuvres and chicken and ice cream while watching the game. "Roy, I want to congratulate you; it shows so much imagination", he was heard to say. Later, he called the stadium "massive" and "beautiful." Although the president's visit overshadowed all others, dignitaries swarmed through the "Eighth Wonder of the World" during the three days of the exhibition series and for opening night against the Phillies.
The first artist to play the Astrodome was Judy Garland on December 17, 1965, where she was paid $43,000 for the one show. The Supremes were her opening act and tickets were priced $1.00 to $7.50. The dome seated 48,000, with another 12,000 seats added for this show. Garland appeared on stage at 10 p.m. and sang for 40 minutes, with her set of songs including: "He's Got The Whole World In His Hands"; "Just In Time"; "My Kind Of Town, Houston Is"/"Houston"; "As Long As He Needs Me"; "Joey, Joey, Joey"; "Do It Again"; "What Now My Love?"; "By Myself"; "Rock-A-Bye Your Baby"; "San Francisco"; "Chicago"; and "Over The Rainbow." Mort Lindsey conducted.
June 15, 1976 "The Rainout"
Ironically, the Astrodome suffered a rainout on June 15, 1976. The Astros' scheduled game against the Pittsburgh Pirates was called when massive flooding in the Houston area prevented all but a few fans from reaching the stadium. Both teams had arrived early for practice, but the umpires were several hours late. At 5pm that day, with only a handful of fans on hand and already several hours behind, the umpires and teams agreed to call the game off. Tables were brought onto the field and the teams ate dinner together. Although the Astros still had a home series with Pittsburgh in August, this game was made up in Pittsburgh in July.
Recent history
In 1989, four cylindrical pedestrian ramp columns were constructed outside the Dome for accessibility. This enabled the Astrodome to comply with the Americans with Disabilities Act of 1990.
The 1992 Republican National Convention was held at the Astrodome in August of that year. The Astros accommodated the convention by taking a month-long road trip.
On August 19, 1995, a scheduled preseason game between the Oilers and the San Diego Chargers had to be canceled due to the dilapidated condition of the playing field. Oilers owner Bud Adams demanded a new stadium, but the city of Houston refused to fund it. After years of threats, Adams moved the team to Tennessee after the 1996 season. Around that time the Astros also threatened to leave the city unless a new ballpark was built. The retractable-roofed Enron Field (now known as Minute Maid Park) opened for the 2000 season in downtown Houston.
One of the largest crowds in the Astrodome's history, more than 66,746 fans, came on Sunday, February 26, 1995, to see Tejano superstar Selena and her band Los Dinos perform for a sell-out crowd during the Houston Livestock Show and Rodeo. Selena y Los Dinos performed two consecutive times before at the Astrodome, breaking previous attendance records each time. This was Selena's last televised concert before she was fatally shot on March 31, 1995 by her fan club president.
The Astrodome was joined by a new neighbor in 2002, the retractable-roofed Reliant Stadium (now known as NRG Stadium), which was built to house Houston's new NFL franchise, the Houston Texans. The Houston Livestock Show and Rodeo moved to the new venue in 2003, leaving the Astrodome without any major tenants. The last concert at the Astrodome was George Strait & the Ace in the Hole Band during the 2002 Houston Livestock Show and Rodeo, before a record crowd of 68,266; the performance was recorded in For the Last Time: Live from the Astrodome.
Hurricane Katrina
On August 31, 2005, in the wake of Hurricane Katrina, the Harris County Department of Homeland Security and Emergency Management and the State of Louisiana came to an agreement to allow at least 25,000 evacuees from New Orleans, especially those that were sheltered in the Louisiana Superdome, to move to the Astrodome until they could return home. The evacuation began on September 1, 2005. All scheduled events for the final four months of 2005 at the Astrodome were cancelled. Overflow refugees were held in the surrounding Reliant Park complex. There was a full field hospital inside the Reliant Arena, which cared for the entire Katrina evacuee community.
The entire Reliant Park complex was scheduled to be emptied of hurricane evacuees by September 17, 2005. Originally, the Astrodome was planned to be used to house evacuees until December. However, the surrounding parking lots were needed for the first Houston Texans home game. Arrangements were made to help Katrina evacuees find apartments both in Houston and elsewhere in the United States. By September 16, 2005, the last of the hurricane evacuees living in the Astrodome had been moved out either to the neighboring Reliant Arena or to permanent housing north of Houston. As of September 20, 2005, the remaining Katrina evacuees were relocated to Arkansas due to Hurricane Rita.
Maps Astrodome
Closure
In 2008, the facility was cited for numerous code violations. Since then, only maintenance workers and security guards have been allowed to enter the stadium while it is brought up to code. The city council rejected demolition plans on environmental grounds, over concerns that demolition of the Dome might damage the dense development that today closely surrounds it.
Refurbishment plans
Houston's plan to host the 2012 Summer Olympics included renovating the Astrodome for use as a main stadium. Houston became one of the USOC's bid finalists, but the organization chose New York City as its candidate city and the Games were ultimately awarded to London by the IOC.
Plans to convert the Astrodome into a luxury hotel were rejected. A proposal to convert the Astrodome into a movie production studio was also considered but rejected. Regardless of the type of renovation, all renovation plans must deal with the problem of occupancy code violations that have basically shuttered the Astrodome for the near future.
In June 2013, a comprehensive plan was unveiled that would have seen the aging structure undergo an almost $200 million renovation into a multi-purpose event/convention facility. The measure would have to have been approved first through a bond election in Harris County for the publicly funded project to go forward or else, officials warned, the iconic structure would be demolished. Voters ended up rejecting the measure on November 5, 2013.
2013 referendum and aftermath
On November 5, 2013, voters in Houston turned down a $213 million referendum to renovate and convert the Astrodome into a state-of-the-art convention center and exhibition space known as "New Dome Experience". Until a final disposition is made, Harris County commissioners will not approve demolition of the stadium. "The building's still there. There's no formal plan or authorization to demolish the building, and until somebody brings such a plan to fruition, there's a chance," according to Willie Loston, executive director of the Harris County Sports and Convention Corporation. "The proposal was rejected by the voters. We're back to where we were. Square one," according to Steve Radack, Harris County commissioner.
Three exterior pedestrian ramp towers were demolished on December 8, 2013. Around that time, the ramp bridges were disconnected from the main structure and the surrounding grass berms were lowered. The ticket booths were also removed along with the interior seats. The demolition was planned prior to the referendum.
Astrodome Indoor City Park
After the failed bond election of 2013, the county went back to the drawing board and in August 2014 the County Commissioners Court announced a new plan to save and rejuvenate the Astrodome. The new concept centered around leaving the Dome's roof intact and converting the Astrodome's vast central space into a covered semi-climate-controlled city park that could have flexible uses for both public recreation and gatherings such as festivals and concerts. The remainder of the complex would have been redeveloped over time using a combination of public and private funds and include elements such as an educational exploration area to encourage students to learn about the sciences and engineering and possibly meeting, exhibition, and restaurant areas that would not only serve the general public, but could also add value to the Houston Texans' Game Day Experiences and be used by the Rodeo. A key element of this proposal centered around the ability for the county to proceed with the initial phases of the project using existing funds without having to seek voter approval for an expensive bond referendum. However, this plan failed as well.
Astrodome Revitalization Project
After the failed plans of past years, the Astrodome Revitalization Project was proposed in September 2016. This plan would turn the dome into a massive underground parking garage. Specifically, the first step would raise the dome floor and use the space underneath that as parking, leaving the floor above for other uses. On September 27, 2016, the Harris County Commissioners approved the first part of the plan. This marked a major turning point for the dome as some feared if the plan wasn't approved the building would be demolished. On January 27, 2017, the Texas Historical Commission voted unanimously to designate the dome a State Antiquities Landmark. Under the designation, the Astrodome may no longer be removed, altered, damaged, salvaged, or excavated without a permit from the commission.
Notable events
Baseball
- The first home run in the Astrodome was hit by Mickey Mantle off of pitcher Turk Farrell on April 9, 1965 in an exhibition game between the Astros and Yankees. The first official home run was hit by Dick Allen of the Philadelphia Phillies in a game on April 12 of that year - a 2-0 Astros loss.
- Lindsey Nelson, an announcer for the visiting New York Mets, broadcast a game on April 28, 1965 while perched in a gondola suspended from the roof above second base.
- At the beginning of the 1980 play off series between the Astros and the Phillies, KILT AM radio announced that the Astros number one fan "Astroman" would live on top of the Domed stadium and would not come down until the Astros won the World Series. Over the next 10 days Astroman, played by KILT salesman Denver Griffith, lived on top of the Astrodome in a six-man tent. On top of the Astrodome was also a telephone hot line back to KILT radio where Griffith as Astroman would give interviews throughout the day. Astroman was completely cut off and could only get food and drink by lowering a rope with a basket the 18 stories from the top of the Astrodome to the center of the playing field. At one point Griffith got so desperate for food and drink that his mother had to intervene and interrupt an Oilers practice so that the needed supplies could be delivered. Every night a local TV station would sign off with a shot of Astroman on top of the Astrodome waving to a circling news chopper.
- On October 15, 1986 the Astros and the visiting New York Mets played Game 6 of the 1986 NLCS. The 16-inning contest was at the time the longest game in MLB post season history. The Mets would take a 7-4 lead into the bottom of the 16th inning and hold on for a 7-6 victory over the Astros. Ironically, the record was broken in Houston 19 years later at Minute Maid Park during the 2005 NLDS when the Astros won an 18-inning game against the Atlanta Braves.
- On October 3, 1999, the Astros played their final regular season game at the Astrodome, clinching the NL Central Division title with a 9-4 win over the Dodgers. The final Astros game in the stadium occurred 6 days later when the Braves eliminated the Astros in Game 4 of the Division Series.
Basketball
- The Game of the Century between the University of Houston Cougars and the UCLA Bruins took place at the Astrodome on January 20, 1968 before a crowd of 52,963--the record for the largest attendance ever at a basketball game until 2003. The first National Collegiate Athletic Association regular season game broadcast nationwide in prime time, the Game of the Century established college basketball as a sports commodity on television, and paved the way for the modern "March Madness" television coverage. The Cougars, coached by Guy V. Lewis, defeated coach John Wooden's Bruins, led by Lew Alcindor, 71-69 behind a 39-point scoring effort from Elvin Hayes.
- The Astrodome hosted the 1989 NBA All-Star Game. Attendance was 44,735 and Karl Malone won MVP honors.
Tennis
The Battle of the Sexes tennis match occurred on September 20, 1973, aired on ABC with Billie Jean King defeating the late Bobby Riggs in three straight sets. While more of a publicity stunt than a serious match, it made national headlines and stands as a milestone in the progress of women's sports. Scenes were filmed here in the 2017 film Battle Of The Sexes which starred Emma Stone & Steve Carell, who respectively played these players.
Boxing & WWE
- Three-time World Heavyweight Boxing Champion Muhammad Ali fought Cleveland Williams in the Astrodome in November 1966.
- On April 1, 2001, the WWE (then known as the WWF) hosted WrestleMania X-Seven, which set an all-time record attendance for the Astrodome of 67,925. The main event of the card saw Texas native "Stone Cold" Steve Austin challenge and defeat WWF Champion The Rock in a No Disqualification Match for The Rock's Championship. The card also featured the first of Houston native The Undertaker's three WrestleMania victories over Triple H, and the first Tables, Ladders and Chairs Match between Edge & Christian, The Dudley Boyz and The Hardy Boyz. The card is perceived by many fans and wrestling historians to be the greatest WrestleMania ever.
Concerts
- Elvis Presley gave six performances there between February and March 1970, setting an attendance record with 200,000 over the six shows. He performed there again on March 3, 1974, setting a single day attendance record.
- September 4, 1992; Co-headlining tour of Metallica and Guns N' Roses with special guest Faith No More. News footage of this concert can be found on YouTube at https://www.youtube.com/watch?v=4CsH-TnpBdI. Additionally, MTV filmed an episode of Live n' Loud during the show. Footage from that can also be seen here: https://www.youtube.com/watch?v=Uw3NU8J_zal
Motorsports
The Astrodome held several motorsports events throughout its lifetime. The AMA Grand National Championship held events starting in 1968 and running for 18 years, utilizing the Short Track and TT Steeplechase track configurations in their visits. The AMA Supercross Championship held its first ever indoor Supercross at the Astrodome in 1974, won by Jim Pomeroy. In the mid-1980s the Mickey Thompson Entertainment Group held several Stadium Off-Road Racing Series events, showcasing such drivers as Ivan Stewart, Robby Gordon, and Walker Evans. Beginning in the early 1980s, both TNT Motorsports and the United States Hot Rod Association held events showcasing mud bogging, truck and tractor pulling, and monster trucks in the Astrodome. After a buy-out of TNT Motorsports, the USHRA continued holding events that would later transform into the current Monster Jam events.
With the opening of NRG Stadium in late 2002, the events held in early 2002 by AMA Supercross and Monster Jam would be their last in the Astrodome before moving next door for 2003, where they continue to hold events every year.
- KTRK-TV Channel 13 Eyewitness News anchorman Dave Ward was injured during a motocross exhibition race (which also included Channel 13 sports anchor Bob Allen, as well as other local media figures) in the Astrodome in the early 1970s.
- Evel Knievel jumped 13 cars two nights in a row, drawing over 100,000 spectators to the Astrodome in January 1971, and though there was talk of him making an actual jump over the stadium itself sometime in the future, it never happened.
- The Astro Spiral car jump was performed January 12, 1972, by Chick Galiano of J.M. Productions' Hell Drivers. This stunt was later performed in the 1974 James Bond film The Man With The Golden Gun.
In popular culture
- Robert Altman's 1970 comedy film Brewster McCloud is set at the Astrodome: the eponymous hero is an eccentric young man who lives at the stadium.
- The 1972 special Road Company was videotaped here, which starred Dom DeLuise, Bob Hynes and Sheila MacRae.
- The Astrodome was the setting for the filming of an exhibition game with the fictional Houston Toros in the 1977 movie The Bad News Bears in Breaking Training.
- The made-for-TV movie Murder at the World Series was filmed here, about a fictional 1977 World Series between the Astros vs. Oakland Athletics.
- In 2001, U2 filmed the music video for "Stuck in a Moment You Can't Get Out Of" inside the Astrodome.
- In 2004, the Astrodome was the setting of the 1988 5A Football State Championship in the movie Friday Night Lights, between the Permian Panthers and the Carter High Cowboys.
Awards and recognitions
- On June 19, 2013, the Astrodome was named to the National Trust for Historic Preservation's annual list of America's 11 Most Endangered Historic Places as well as to its National Treasures portfolio.
- The Astrodome was added to the National Register of Historic Places in January 2014.
- The dome celebrated its 50th anniversary on April 9, 2015. A time capsule buried under the site at the time of construction was located. However, it was not extricated to celebrate the occasion, based on concerns about the cost and potential to compromise the structure of a retaining wall. This was also one of the very few times that the Astrodome has been open for the public since 2006.
Features
Scoreboard
The Astrodome was well-renowned for a four-story scoreboard called the "Astrolite", composed of thousands of light bulbs that featured numerous animations. After every Astros home run, the scoreboard featured a minute-long animated celebration of pistols, bulls, and fireworks. The scoreboard remained intact until 1988 when Houston Oilers (now Tennessee Titans) owner Bud Adams suggested the removal of the scoreboard to accommodate increased capacity demands for football, baseball and the Houston Livestock Show and Rodeo. Harris County spent $67 million of public funds on renovations. Approximately 15,000 new seats resembling the 1970s rainbow uniform pattern were installed to bring seating capacity to almost 60,000 for football. On September 5, 1988, a final celebration commemorating the scoreboard occurred prior to expansion renovations.
Playing surface
Originally, the stadium's surface was a Tifway 419 Bermuda grass, specifically bred for indoor use. The dome's ceiling contained thousands of semitransparent panes made of Lucite. Players quickly complained that glare coming off of the panes made it hard for them to track fly balls; to solve the problem, two sections of panes were painted white in April. However, within a few months, the grass died from lack of sunlight. For most of the 1965 season, the Astros played on green-painted dirt and dead grass. The clear panels also added a problem when combined with the natural grass. The grass tended to hold, then release moisture, often resulting in rain within the structure, causing games to be delayed while the grounds crews cleaned up the playing surface.
The solution was to install a new type of artificial grass on the field, ChemGrass, which became known as AstroTurf. Because the supply of AstroTurf was still low, only a limited amount was available at the start of the 1966 season. There was not enough for the entire outfield, so the first phase covered only the traditional grass portion of the infield and foul territory, at a cost of $2 per square foot. It was installed in time to test out during exhibition games against the Dodgers in March. The outfield remained painted dirt until after the All-Star Game. The team was sent on an extended road trip before the break, and on July 19, the installation of the outfield portion of AstroTurf was completed for a game with the Phillies, thus covering the entire field with AstroTurf. Groundskeepers dressed as astronauts kept the turf clean with vacuum cleaners between innings. The infield dirt remained in the traditional design, with a large dirt arc, similar to natural grass fields.
In 1973, the Astros installed an all-AstroTurf infield, except for dirt cutouts around the bases. This "sliding pit" configuration was introduced by Cincinnati with the opening of Riverfront Stadium on June 30, 1970. It was then installed in the new stadiums in Philadelphia in 1971, and Kansas City in 1973. The artificial turf fields of Pittsburgh, St. Louis, and San Francisco, all installed in 1970, were traditionally configured like the Astrodome and later changed to sliding pits. San Francisco converted in 1971, Pittsburgh in 1973, and St. Louis in 1978. Rogers Centre in Toronto was the last park in the majors that had sliding pits; it opened in 1989 and switched to a traditional dirt skin infield in 2016.
Throughout its history, the Astrodome was known as a pitcher's park. The power alleys were never shorter than 370 feet (113 m) from the plate; on at least two occasions they were as far as 390 feet (119 m). Over time, it gave up fewer home runs than any other park in the National League. The Astrodome's reputation as a pitcher's park continued even in the mid-1980s, when the fences were moved in closer than the Metrodome, which was long reckoned as a hitter's park.
Seating capacity
See also
- List of tennis stadiums by capacity
- National Register of Historic Places listings in Harris County, Texas
- Delta Dome
References
Further reading
- Chandler, Adam. "The Sad Fate (But Historic Legacy) of the Houston Astrodome." The Atlantic. November 8, 2013.
- Trumpbour, Robert C., and Kenneth Womack. The Eighth Wonder of the World: The Life of Houston's Iconic Astrodome (Lincoln, NE: University of Nebraska Press, 2016).
External links
- Carlton, Harold (1968). "The 8th Wonder of the World--The Houston Astrodome". Sunday Times Magazine. London.
- Smith, Liz (April 12, 1965). "Giltfinger's Golden Dome". Sports Illustrated. Archived from the original on December 11, 2012.
- Sarnoff, Nancy (April 26, 2010). "The Astrodome: 'Houston's Eiffel Tower'". Houston Chronicle.
- Historic American Engineering Record (HAER) No. TX-108, "Houston Astrodome, 8400 Kirby Drive, Houston, Harris County, TX"
Source of article : Wikipedia