Orlando is a city in the U.S. state of Florida and the county seat of Orange County. Located in Central Florida, it is the center of the Orlando metropolitan area, which had a population of 2,802,570, according to U.S. Census Bureau figures released in July 2017. These figures make it the 24th-largest metropolitan area in the United States, the sixth-largest metropolitan area in the Southern United States, and the third-largest metropolitan area in Florida. As of 2015, Orlando had an estimated city-proper population of 277,173, making it the 73rd-largest city in the United States, the fourth-largest city in Florida, and the state's largest inland city. The City of Orlando is nicknamed "The City Beautiful," and its symbol is the fountain at Lake Eola. Orlando is also known as "The Theme Park Capital of the World" and in 2016 its tourist attractions and events drew more than 72 million visitors. The Orlando International Airport (MCO or OIA) is the thirteenth-busiest airport in the United States and the 29th-busiest in the world. As one of the world's most visited tourist destinations, Orlando's famous attractions form the backbone of its tourism industry. The two most significant of these attractions are Walt Disney World, opened by the Walt Disney Company in 1971, and located approximately 21 miles (34 km) southwest of Downtown Orlando in Bay Lake; and the Universal Orlando Resort, opened in 1999 as a major expansion of Universal Studios Florida. With the exception of Walt Disney World, most major attractions are located along International Drive with one of these attractions being the famous Orlando Eye. The city is also one of the busiest American cities for conferences and conventions; the Orange County Convention Center is the second-largest convention facility in the United States. Like other major cities in the Sun Belt, Orlando grew rapidly from the 1980s up into the first decade of the 21st century. Orlando is home to the University of Central Florida, which is the largest university campus in the United States in terms of enrollment as of 2015. In 2010, Orlando was listed as a "Gamma−" level global city in the World Cities Study Group's inventory. Orlando ranks as the fourth-most popular American city based on where people want to live according to a 2009 Pew Research Center study.