This is the building where their apartment was located, a close-up of which was shown at the very beginning of each Milwaukee episode's intro, when Laverne & Shirley sang:♫ 1, 2, 3, 4, 5, 6, 7, 8, schlemiel, schlimazel, Hasenpfeffer Incorporated... ♫
This building (called Block A) is still located on Washington Square, on the back lot at Paramount Pictures Studios in Hollywood, California.
Although all units in this building look identical, my yellow flag-pin points to the steps of Laverne & Shirley's actual unit.
This is NOT where any episodes were filmed; this building was ONLY used for the opening credits, and a few outside shots during certain episodes.
The actual episodes were filmed on Stage 20, at the front of Paramount Pictures Studios.
jericl cat (Flickr) 6TH July 2011 Hollywood, California Paramount Pictures Studios Back lot About 60' north-east of Laverne & Shirley's apartment building John Mark Motyer, CD