The AP on Virtual Rome: "Computer experts on Monday unveiled a digital reproduction of ancient Rome as it appeared at the peak of its power in A.D. 320 — what they called the largest and most complete simulation of a historic city ever created." The official site is at the University of Virginia's Rome Reborn 1.0.
A Jerusalem Reborn project is also under way, though its completion seems to be a long ways away. You can see the initial work being done on their construction of the second temple.
Speaking of Herod's Temple, one of the most helpful things on the web is this virtual reconstruction model from the Davidson Center. It allows you to "stand" in the temple court and have a look around. It will surely give you a new appreciation for the size and scope of the temple mount!