Album Cover
Building pictured on the cover of the Led Zeppelin album "Physical Graffiti":

96 and 98 St. Mark's Place
Although the building has five stories, one was cropped to make the picture fit the proportions of the album cover.
Source: The New York Times, 9/8/2002

 
   
  Words purportedly heard when the Led Zeppelin's "Stairway to Heaven" is played backwards:

"Here's to my sweet Satan."
According to Jeff Milner, who runs a website which tracks what is called "backmasking", the words are specifically heard when the line "a bustle in a hedgerow" is played backwards.
Source: Wall Street Journal, 1/9/2006

 
   
  Led Zeppelin gives its last concert:

West Berlin (July 7, 1980)
Led Zeppelin's last concert was on July 7, 1980 in Berlin at the Berlin Eissporthalle.
Source: Toronto Sun, 7/7/2001

 
   
  Date the first member of the band died:

Sept. 25, 1980
On Sept. 25, 1980, Led Zeppelin drummer John Bonham was found dead in bed in a home owned by Jimmy Page. He was 32 years old.
Source: New York Times, 9/26/1980