Everyone knows about Powell's City of Books, but much less famous is their technical bookshop on Park in Downtown Portland. They carry law, construction, architecture, and medical books/journals, and probably a lot more that I'm unaware of. The selection is huge and this shop is less crazy than their big location a few blocks away. The staff will special order anything you need. Returns are a breeze and the buy-back process here is easier than at the store on Burnside. If you're in a specialized field, you must check out Powell's Technical Books!