you can take a look at the drawings architects themselves make, "Frank Lloyd Wright Designs" is a great book or you can just google his drawings : )) there's stuff about buildings' perspective in Francis Ching's "Architectural Graphics", you can also take a look at his ink drawings and for colorful stuff - there's a chinese book with amazing marker drawings, "Architecture Color Rendings by Marker Pen", it's pretty easy to find on the net) there's yet another book i remember with colorful elevations of victorian architecture i think it was? they were really beautiful but i don't remember the author, i'll get back to you if i find out what book that was) i hope this helps you :>
There are many books and websites out there on real life 'fantasy' artwork, though I don't know them by name. You'd want to keep an eye out for Medieval to Victorian styles - Rococo (very whimsical/fantasy-like) Gothic, and so much more. Try searching for images of these names on the Internet + adding 'architecture' with the search.