The Tenderloin is San Francisco's most notorious neighbourhood, a dense grid of single-room-occupancy hotels and old apartment blocks just west of Union Square. It has long been the city's hard centre — visible poverty, open-air drug dealing, and homelessness are part of daily life here, and many visitors are warned off it entirely. That reputation is not unearned, and it pays to keep your wits about you, stick to busier streets, and be cautious after dark.
Look past the hardship, though, and the Tenderloin is one of the most vital and interesting corners of the city. It is a genuine immigrant neighbourhood — Little Saigon along Larkin Street, a run of cheap Pakistani halal kitchens where cab drivers eat, Vietnamese, Thai, and Indian restaurants on nearly every block. It has grand survivors from before the district's decline — the Great American Music Hall and hidden speakeasies — and a deep tradition of activism centred on Glide Memorial Church. Come in daylight, come hungry, and you will find some of the best-value eating in San Francisco.