I really like the Virtual field trips lesson, but I would recommend using the Google World Wonders Project as a starting point.
With the Street View technology the Cultural Institute made a lot of Unesco heritage sites accessible, both from modern and ancient times. Of course your students can have a good look around, but they’ll also get in-depth info and additional photos & videos and even 3-d models. If you click on the education tab in the right hand corner, you’ll find educational packages for primary and secondary available for download. They contain lesson plans and worksheets;
The site exists in English, French, Italian, Spanish, Chinese and Arabic (these last two are an educated guess, because I can’t read these languages; please correct me if I’m wrong).
Anyway, the video below will give you a quick overview of what is possible. Happy travels!