The NRG Astrodome, formerly and also known as the Houston Astrodome or simply the Astrodome, was the world's first multi-purpose, domed sports stadium, located in Houston, Texas, United States. It sat around 50,000 fans, with a record attendance of 68,266 set by George Strait in 2002.

A multi-purpose stadium is a type of stadium designed to be easily used for multiple types of events. While any stadium could potentially host more than one type of sport or event, this concept usually refers to a specific design philosophy that stresses multifunctionality over specificity. It is used most commonly in Canada and the United States, where the two most popular outdoor team sports—Canadian football or American football and baseball—require radically different facilities. Football uses a rectangular field, while baseball is played on a diamond with a large outfield. Since Canadian football fields are larger than American ones, the design specifications for Canadian facilities are somewhat less demanding. The particular design to accommodate both is usually an oval, although some later designs use an octorad. While building stadiums in this way means that sports teams and governments can share costs, it also presents some challenges.