From Bill Thayer and Jona Lendering at New at LacusCurtius & Livius:
2300 Ancient Sites on Google Earth
On several occasions I have blogged on the possibilities of Google Earth and its online spin-off, Google Maps. My last blog on this topic was a bit over half a year ago, when I had some 1700 items available. In the meantime, I have added more than 550 ancient sites to my list, from all quarters of the ancient world.
The online version is here and the masterfile can be downloaded here. If you use the latter, do not forget the directory NEW/OFF-TOPIC, which contains many others, still unqualified markers.
And see AWOL's Roundup of Resources on Ancient Geography