Photosynth - Unlike Google Maps and Google Earth, Photosynth is good for interior, panoramic imagery. Mostly of well known places (e.g., the Sistine Chapel) but these do give you a sense of being there.
TinEye Reverse Image Look-Up: This is a new site, so there's still a lot of kinks in it, but you can upload an image to it and it'll find other places on the web where this image is. It's great if you have a picture you want to find out more about.
Note: Architectural information also tends to be regional and the following are just a few examples. You might also look for travel guides or histories of specific cities or regions.