Concluding our survey of the Brooklyn Public Library's photographs of historic theaters in Park Slope is this great view of the Prospect Theater. The BPL cites 1914 as the date of the photograph:
According to our research, the theater was built in 1914, so this very early image shows the building in its original condition, including domes and cornice, now gone. Also note the handsome street lights progressing up 9th Street.
The theater building extends all the way through the block to 8th Street. The front is now a C-Town supermarket, and the back has been converted to apartments, whose residents enter through the original stage door in 8th Street: