San Francisco districts are defined by the SF MLS so there are definite borders. The Tenderloin as defined by SFAR is bounded by Market, McAlllister, Polk, Geary and Mason. California between Hyde and Larkin is the boundary for Nob Hill and the Downtown districts. Trader Joeâ€™s has recently opened a wonderful new store in that block on the south side of California, the Downtown District. It is a safe area. The cable car runs up and down California all the way from Van Ness to Market Street near the Embarcadero right past the block in question. Lots of tourists and residents in the area.