Is the alley in question Green Court, off 14th near Thomas Circle? I worked in one of the buildings on 14th and could look out on the alley which then, the '90s, housed the Green Lantern, a gay club. I think it became the Tool Shed.

Ahh, yes, looks like my hunch was correct...

From "Gay Life Remembered" by Bob Roehr in Independent Gay Forum...

Krazy Kat in 1920 was a "Bohemian joint in an old stable up near Thomas Circle ... (where) artists, musicians, atheists, professors" gathered. Miraculously the structure still stands, five blocks from the White House, as a gay bar called the Green Lantern.