"We go into old Susy’s place"

The Brothel
Public DomainThe Brothel - Credit: Vincent van Gogh
Old Susy’s place is clearly a brothel.

Prostitution was legal in California at this time, with female prostitutes often living and working together in an establishment run by a madam (the woman in charge, usually not a prostitute herself).

Prostitution is now illegal in the United States, other than in some Nevada counties.