San Francisco is a version of seven card stud. Actually, there are two separate games: High San Francisco and Low San Francisco. The rules for dealing each player's up and down cards as well as the betting sequences are the same as in normal 7 card stud.
In High San Francisco, the pot is split at showdown between the highest normal stud hand and the hand containing the highest heart. In Low San Francisco, it's the lowest heart that divides up the pot with the highest poker hand. Aces count only for high for this purpose.
You probably won't encounter San Francisco in any public card establishments, but you might find it in home games.