Off the Grid and Gothamist both had posts to commemorate the occasion ... and offer up some history.
And you probably know the connection to the album here. We'll let Off the Grid sum it up:
Led Zeppelin immortalized the twin tenements at 96 and 98 St. Mark’s Place between First Avenue and Avenue A on the Physical Graffiti album cover. The award-winning design featured the two buildings (with the fourth floors removed to make them fit the square shape of the album cover) with the windows cut out to reveal the letters of the album title printed on the inner sleeve, or, if the sleeve was reversed, a series of images of different characters seeming to occupy the building, including lead-singer Robert Plant in drag.
Previously on EV Grieve:
Fire scare on St. Mark's Place at iconic Physical Graffiti building
I'm not waiting on a lady...say, what the hell is Mick wearing anyway?
[Photos via Off the Grid]