If taking photos for use in a self published book, obtain model and property releases as necessary. (toughnickel.com)
While you may be interested in the architecture for purely aesthetic reasons, many places forbid the snapping of photos for reasons of terrorism and more. (travelinsurancereview.net)
Obviously this is just my opinion but I've been taking photos for more than 20 years and have never come close to this. (arsenalfcblog.com)