Swensen’s Ice Cream is the original ice cream shop opened in 1948 that gave rise to the Swensen’s Ice Cream Factories and Restaurants chain, which had more than 400 stores in the USA at one point. The San Francisco store was never part of the chain (which is now all but gone in the USA) (the chain has about 300 outlets now internationally).
The store is open from noon to 10 pm most days, and noon to 11 pm Friday and Saturday. You will encounter Swensen’s if you are walking on Hyde Street towards Lombard Street.
Swensen’s only accepts cash.
Totally worth a visit.