If you're coming to Pittsburgh, seeing the bridges is a must.  Pittsburgh is home the most bridges of any city in the world!  (Including Venice, Italy; St. Petersburg, Russia; and Paris, France)  Starting in downtown with the Fort Pitt on the Monongahela and the Fort Duquesne on the Allegheny, it is easy to make your way up each respective river.  A good resource for driving tours of river and inland bridges is The Bridges of Pittsburgh by Bob Regan.  You can find it at  any Barnes and Noble in Pittsburgh!