The color of the Guggenheim's facade has been discussed over and over again, but did you know that Frank Lloyd Wright designed it to be red? More specifically, "Exterior: Red-marble and long-slim pottery red bricks."
The NY Times reports that Hilla Rebay, art adviser to Solomon R. Guggenheim, responded to the color choice (which was also represented in a model) saying, “Red is a color which displeases S. R. G. as much as it does me," suggesting yellow or green instead. The architect uncharacteristically backed down saying that any color would be acceptable.
By 1952 Wright proposed a white concrete and polished marble gravel exterior, which didn't go through due to budget issues, and that is when the PV020 Buff was decided upon. The paper notes that "By the time of the opening in October 1959, Wright was dead and the color had been changed on the job to a tint of cream and very soft yellow," something that Robert Moses said looed like "jaundiced skin."
The museum is currently housing their Frank Lloyd Wright: From Within Outward exhibit, in celebration of the building's 50 year anniversary.