San Antonio's economy is principally based on healthcare, defense, financial services, and tourism. Just to the Northwest of the city center is the South Texas Medical Center, which is a conglomeration of hospitals, clinics, educational and research establishments, and which in total employs over 27,000 people. Meanwhile The defense industry in San Antonio employs over 89,000 people, and additionally there is a large military presence in the area, including the bases at Brooks City-Base, Fort Sam Houston, Lackland Air Force Base and Randolph Air Force Base, all within the city, and Camp Bullis and Camp Stanley just outside the city.
San Antonio is a popular tourist destination, visited by more than 20 million tourists each year. Attractions in San Antonio include the SeaWorld San Antonio and the Six Flags Fiesta Texas theme parks. Also popular is the River Walk (also known as "Paeo del Rio"), which is a network of walkways in the downtown area around the San Antonio River, and contains many shops, restaurants and bars.
Finally, any description of tourism in San Antonio, can not go without mentioning the San Antonio de Valero Mission, which is popularly simply known as "The Alamo". Today a museum, the Alamo is a former mission and fortress which was the sight of several battles, including most famously the 1836 Battle of the Alamo, one of the key battles fought between the Republic of Texas and Mexico during the Texas Revolution.
