Downtown is the largest central business district in the city of Houston and the largest in the state of Texas, located near the geographic center of the metropolitan area at the confluence of Interstate 10, Interstate 45, and Interstate 69. The district, enclosed by the aforementioned highways, contains the original townsite of Houston at the confluence of Buffalo Bayou and White Oak Bayou, a point known as Allen's Landing. Downtown has been the city's preeminent commercial district since its founding in 1836. Today home to nine Fortune 500 corporations, Downtown contains of office space and is the workplace of 150,000 employees. Downtown is also a major destination for entertainment and recreation. Nine major performing arts organizations are located within the 13,000-seat Theater District at prominent venues including Alley Theatre, Hobby Center for the Performing Arts, Jones Hall, and the Wortham Theater Center. Two major professional sports venues, Minute Maid Park and the Toyota Center, are home to the Houston Astros and Houston Rockets, respectively. Discovery Green, an urban park located on the east side of the district adjacent to the George R. Brown Convention Center, anchors the city's convention district. Downtown is Houston's civic center, containing Houston City Hall, the jails, criminal, and civil courthouses of Harris County, and a federal prison and courthouse. Downtown is also a major public transportation hub, lying at the center of the light rail system, park and ride system, and the metropolitan freeway network; the Metropolitan Transit Authority of Harris County (METRO) is headquartered in the district. Over 100,000 people commute through Downtown daily. An extensive network of pedestrian tunnels and skywalks connects a large number of buildings in the district; this system also serves as a subterranean mall. Geographically, Downtown is bordered by East Downtown to the east, Third Ward to the south, Midtown to the southwest, Fourth Ward to the west, Sixth Ward to the northwest, and Near Northside to the north. The district's streets form a strict grid plan of approximately 400 square blocks, oriented at a southwest to northeast angle. The northern end of the district is crossed by Buffalo Bayou, the banks of which function as a linear park with a grade-separated system of hike-and-bike trails. Composition Downtown Houston is a area bounded by Interstate 45, Interstate 69/U.S. Highway 59, and Interstate 10/U.S. Highway 90. Several sub-districts exist within Downtown, including: Ballpark – Includes Minute Maid Park and surrounding