I read an article in the Guardian about a virtual recreation of ancient Rome that is the result of a collaboration between Google Earth and the Roman Reborn project. It can be seen at http://earth.google.com/intl/en/rome/ and is certainly worth looking at. You will need to download Google Earth 4.3 if you do not have it. It took me a little while to figure it out, and understand what I needed to do to download the 3D terrain, but it was certainly worth the effort.
RSM
Ancient History Ramblings 