Downtown San Antonio is the central business district of San Antonio, Texas, United States. It also serves as the urban core of Greater San Antonio, a metropolitan area with nearly 2.5 million people.In addition to being encircled by Loops 1604 and 410, Downtown San Antonio is encircled by three Interstate freeways: I-35, I-37, and I-10. Together, the three highways create a rectangular route around the city's urban core: I-35 to the north and west, I-37 to the east, and I-10 to the south. The rectangular loop has a nine-mile circumference and is known as the "Downtown Loop" or "Central Loop", which encompasses both it and Southtown.