Photos you take yourself are *usually* yours but with some exceptions; some buildings are copyrighted and/or trademarked.
The usual criteria in those cases is "commercial gain". For personal use you can do anything but not for sale or for promotional use. i.e., using a picture of Cinderella's castle on the cover of your "historical romance" is probably not going to fly.
Very murky subject:
http://www.copyright.gov/help/faq/faq-protect.html
http://photo.net/bboard/q-and-a-fetc...&msg_id=004im1