The Astrodome, the first fully air-conditioned, enclosed, domed, multipurpose sports stadium in the world, was officially named Harris County Domed Stadium when it opened in April 1965. On average, more than four million persons visited the Astrodome each year between 1965 and 2000. It has been used for major-league baseball, major-league soccer, professional and collegiate football, championship boxing, Portuguese-style bullfighting, rodeos, polo, collegiate basketball, special concerts, conventions, and religious meetings. The Astrodome is the prototype of numerous sports structures, including the Superdome in New Orleans, the Kingdome in Seattle, and the Silverdome in Pontiac, Michigan.
The first tangible efforts toward building the innovative stadium were made when the Harris County Park Commission was established by the Fifty-fifth Texas Legislature. The bill enabled Harris County to submit a revenue-bond issue to property owners for a Houston sports center. Voters approved the issue by a vote of more than three to one on July 26, 1958. Later, the idea of having an all-purpose covered stadium was developed through the leadership of Roy M. Hofheinz, and it was determined that a new bond issue should be held to authorize general-obligation bonds. On January 31, 1961, the voters of Harris County approved a general obligation bond issue of $22 million. Ground was broken on January 3, 1962. After excavation work was completed it was found that more money was needed to complete the structure. On December 22, 1962, another bond issue of $9 million was approved by Harris County property owners. Although there were two lawsuits and other delays, construction on the stadium itself started on March 18, 1963, and was completed two years later. The stadium structure itself cost $20 million but the overall cost was more than $40 million of which $31.6 million came from two county bond issues and $3.75 million from the state highway department and the city of Houston for off-site improvements, including paved streets, bridges, and storm sewers. The Houston Sports Association, which leased the stadium from the county for forty years, added $6 million for expensive apartments, restaurants, cushioned seats, and a $2 million scoreboard.
The first event in the Astrodome was held on April 9, 1965, when the Houston Astros played the New York Yankees in exhibition baseball. The first football game was played in the Astrodome on September 11, 1965, when Tulsa University defeated the University of Houston by a score of 14–0. Professional football established itself in the Astrodome when the Houston Oilers began playing all of their home games there after a preseason exhibition game with the Washington Redskins on August 1, 1968. Seating capacity of the Astrodome for baseball was 52,000, for football about 62,000, and for some events, 66,000. Temperature was a constant 73°F, with humidity at 50 percent. There were five restaurants. The stadium has a clear span of 642 feet, an inside height of 208 feet, a lighting maximum of 300 footcandles, an air-filtering system of activated charcoal, and a man-made field cover called Astroturf. Hofheinz ordered the plastic roof painted because outfielders had trouble tracking fly balls during daylight in the bright glare and criss-cross network of girders overhead. The lack of sunlight kills the grass, but the Chemstrand Company, then experimenting with an outdoor artificial carpet, produced what came to be called AstroTurf. Hofheinz, starting in 1966, used this instead of natural grass. Over time, questions were raised about injuries suffered from the harder surface, although numerous other stadiums elected to use it.
In 1988 and 1989 the dome underwent a $100 million renovation. Seating was expanded by 10,000, seventy-two luxury boxes were built, and four cylindrical pedestrian ramps were added to the exterior of the structure. As well as being the one-time home for both the Houston Astros and Houston Oilers, the stadium has also hosted the United States Football League Houston Gamblers, World Football League Houston Texans, and the University of Houston Cougars. Annual events included the Astro-Bluebonnet Bowl and the Houston Livestock Show and Rodeo. Other notable events include the 1966 heavyweight title fight between Muhammad Ali and Cleveland Williams, the 1968 "Game of the Century" between the UCLA Bruins and the University of Houston Cougars, and the 1973 "Battle of the Sexes" tennis match between Billie Jean King and Bobby Riggs. The stadium also hosted the MLB All-Star Game in 1968 and 1986, the 1971 NCAA Final Four, and the 1989 NBA All-Star Game. In 1992 the Republican party held its national convention at the dome.
Since the late 1990s the Astrodome has experienced a marked decline in use as long-time tenants have relocated to newer venues. The Oilers moved to Tennessee after the 1996 season. The Astros played their last game in the Astrodome on October 9, 1999, after which they moved to the newly constructed Enron Field (now Minute Maid Park), a baseball-only facility, to begin the 2000 season. The Houston Livestock Show and Rodeo relocated to a new venue after 2002, and the dome's last live concert took place in February 2003. When the NFL returned to Houston in 2002, the Houston Texans opened their inaugural season at Reliant Stadium (now NRG Stadium) next door. The Astrodome's final permanent tenant was the Houston Energy of the Women's Professional Football League, who last played there in 2006. In September 2005 the Astrodome served as a temporary emergency shelter for thousands of displaced New Orleans residents after Hurricane Katrina.
In 2009 the Astrodome was permanently closed to the public after the Houston Fire Marshal's Office cited numerous code violations. Since then, proposals to demolish the stadium have competed with a variety of plans to renovate and redevelop the structure into either a luxury hotel, convention space, movie production studio, mall, aquarium, or indoor park. The most ambitious proposal, a $217 million bond measure to convert the dome into a multi-purpose event facility, was rejected by popular referendum in November 2013. To protect against renewed calls for demolition, local preservation groups successfully lobbied to have the Astrodome added to the National Register of Historic Places in January 2014. Then, in September 2016, the Harris County Commissioners Court voted unanimously to approve a $105 million revitalization plan. The first phase of the project will convert underground portions of the stadium into a multi-level parking structure with space for 1,400 vehicles, leaving nine acres of above-ground, indoor floor space available for commercial redevelopment. As of March 2017 construction has not begun; the stadium remains vacant, and is only accessible to maintenance crews. On January 27, 2017, the Texas Historical Commission designated the Astrodome a State Antiquities Landmark, thus making any future alterations to the structure subject to approval from the state government.