According to the US copyright office, all buildings before 1990 are not protected by copyright.
Also, windows, doors, and anything that is a necessary structure of a building are not protected by copyrighted.
http://copyright.gov/circs/circ41.pdfIneligible Building Designs
The following building designs cannot be registered:
• Designs that were constructed, or whose plans or drawings were published,
before December 1, 1990
• Designs that were unconstructed and created in unpublished plans or drawings
on December 1, 1990, and were not constructed on or before December
31, 2002
• Structures other than buildings, such as bridges, cloverleafs, dams, walkways,
tents, recreational vehicles, mobile homes, and boats
Some buildings not protected by copyright in the US:
Empire State Building
Chrysler Building
all buildings built before 1990