The Kingdome was a multi-purpose stadium located in the Industrial District neighborhood of Seattle, Washington, United States. Owned and operated by King County, it was best known as the home stadium of the Seattle Seahawks of the National Football League (NFL) and the Seattle Mariners of Major League Baseball (MLB); it was also home to the Seattle SuperSonics of the National Basketball Association (NBA) and additionally served as both the home outdoor and indoor venue for the Seattle Sounders of the North American Soccer League (NASL). The Kingdome measured 660 feet (200 m) wide from its inside walls.

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.