The Caldron (often misspelled Cauldron) was a sex club for gay men[1] located at 953 Natoma Street in San Francisco's South of Market neighborhood.

"[4] Located in a converted warehouse, the site was unabashedly a place where men went to have sex.

[5] Like other similar venues, it had no alcohol license; patrons brought their own alcohol, usually beer, and this was stored in a cooler and patrons given chits that they could turn in for a can of the brand of beer they had brought.

It was described as "exemplary" as one of the first venues to promote safe sex as the AIDS crisis hit.

[11] The Caldron featured thematic nights, including "J/O party" Tuesdays, "wet Wednesdays" (water sports), and "fist-fucking Thursdays."