Paris 3D Saga is an iPad app that allows students to explore Paris as it was 2,000 years ago up to today.  If students are studying Europe, history, or geography this is an excellent visual app for elementary to high school students.  There is also a web version of this app that is a little more robust.  However, with the web version you will need to install a plugin to run the program.  Both the iPad app and web version are FREE.

The video embedded below is a quick demo of Paris 3D Saga.