The parlor's sign.
The Billiards Parlor was a gaming establishment located just outside of Courthouse Square in 1931. Arthur McFly lived in his apartment directly above it, with his entrance on its right-hand side. Marty McFly and a young Emmett Brown visited Arthur's apartment when trying to subpoena him in their attempt to get Kid Tannen charged. In order to lure Arthur out of his apartment, Marty and Emmett stood underneath the apartment's window, so that they could play a recording of Kid, whom Arthur worked for, yelling orders. Staning underneath this window placed them outside the Billiards Parlor.
By 1986, the location was occupied by Starbase Zero.