an alley between the Sal Sagev (Golden Gate) Hotel building, and 15 Fremont Street. The Lucky 13 Club, and the Keyhole Bar were both located at 13 E. Fremont...and they were located in the Sal Sagev Hotel building.

I don't know what was originally at 15 E. Fremont, but The Northern Club opened there in the 1920's, and was granted the first Clark County gaming license in 1931. Definitely an alley next to the building