http://www.copyright.gov/help/faq/faq-protect.html
"Does copyright protect architecture? Yes. Architectural works became subject to copyright protection on Dec. 1, 1990. The copyright law defines architectural work as the design of a building embodied in any tangible medium of expression, including a building, architectural plans, or drawings. Copyright protection extends to any architectural work created on or after Dec. 1, 1990. Also, any architectural works that were unconstructed and embodied in unpublished plans or drawings on that date and were constructed by Dec. 31, 2002, are eligible for protection. Architectural designs embodied in buildings constructed prior to Dec. 1, 1990, are not eligible for copyright protection." A photograph may not be a "copy" of a building, any more than a photograph is a copy of a sculpture or painting, but if sell a photo of it you're violating copyright. -- Mark Roberts Photography and writing www.robertstech.com

