A multi-purpose stadium is a type of stadium designed to be easily used by 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 – football and baseball – require radically different facilities. Football uses a rectangular field (Canadian football fields are larger than American ones), while baseball is played on a diamond and large outfield. This requires a particular design to accommodate both, usually an oval, while some later designs used an octorad. While building stadiums in this way means that sports teams and governments can share costs, it also imposes some challenges. In North America, multipurpose stadiums were built primarily during the 1960s and 1970s as shared home stadiums for Major League Baseball and National Football League or Canadian Football League teams. Some stadiums were renovated to allow multipurpose configurations during the 1980s. This type of stadium is associated with an era of suburbanization, in which many sports teams followed their fans out of large cities into areas with cheaper, plentiful land. They were usually built near highways and had large parking lots, but were rarely connected to public transit. As multipurpose stadiums were rarely ideal for both sports usually housed in them, they had fallen out of favor by the 1990s, with the SkyDome that opened in 1989 being the last such stadium completed to accommodate baseball and football. With the completion of the Truman Sports Complex in Kansas City in 1973, a model for purpose-built stadiums was laid down. Since Oriole Park at Camden Yards opened in 1992, most major league sports stadiums have been built specifically for one sport. From the late 2000s onward, however, some football specific stadiums that are either domed or open-air (Texas Stadium, RCA Dome, Georgia Dome, and Bank of America Stadium) have been or may be replaced by multipurpose stadiums with a retractable roof (Cowboys Stadium, Lucas Oil Stadium, and Mercedes-Benz Stadium) and even a roll-in natural grass field (State Farm Stadium) where NFL football remains the primary tenant but which can also accommodate other events year-round (soccer, concerts, major conventions, and NCAA Final Four basketball), although not baseball as that demands radically different field dimensions. Likewise some baseball-specific stadiums (Globe Life Park in Arlington and Tropicana Field) have been or were proposed to be replaced by multipurpose stadiums (Globe Life Field, Ybor Stadium), and while still primarily for baseball, the retractable roof allows the venue to host other events year-round. Outside North America, the term is rarely used, since association football is the only major outdoor team sport in many countries; in many countries, association football and rugby can easily co-exist. In Australia, many sports grounds are suited to both Australian rules football and cricket, as Australian rules is played on cricket ovals. In some cases such as Stadium Australia in Sydney, Docklands Stadium in Melbourne and National Stadium, Singapore, stadiums are designed to be converted between the oval configuration for cricket and Australian rules football and a rectangular configuration for Rugby and Association Football and in the case of Singapore's National Stadium, an Athletics configuration as well. Association football stadiums have historically served as track and field arenas, as well, and some (like the Olympiastadion in Berlin) still do, whereas a newer generation frequently has no running track to allow the fans closer to the field. Among winter sports, especially a speed skating rink can be a multi-purpose stadium. Very often a rink or two of approximately the size 61 × 30 metres – the regulation size of an IIHF ice hockey rink - are placed inside the oval. Sometimes the ice surface is even larger, allowing for also bandy and curling.