The Tenderloin is a neighborhood in downtown San Francisco, in the flatlands on the southern slope of Nob Hill, situated between the Union Square shopping district to the northeast and the Civic Center office district to the southwest. Encompassing about 50 square blocks, it is historically bounded on the north by Geary Street, on the east by Mason Street, on the south by Market Street and on the west by Van Ness Avenue. The northern boundary with Lower Nob Hill has historically been set at Geary Boulevard.