You should add Malta to your list - best archaeological sites that I have seen. Stone structures several years older than Stonehenge; beautiful objects in the archaeological museum in Valletta. Bonus - Malta is relatively cheap and can be visited from Sicily as a daytrip or overnight or by cheapish flights from Britain.

Be sure to see Hal Saflieni Hypogeum, an underground structure which was first in use around 3600 BC. Spectacular, moving experience. Restricted visiting. See their page. http://www.heritagemalta.org/hypogeum.html

About.com's page on Malta and archaeology: http://tinyurl.com/28r4g

http://www.heritagemalta.org/visiting.html

Old Temples Study Foundation: http://www.otsf.org/introduction.html

For a general list of heritage sites, see UNESCO's World Heritage sites (includes Malta): http://whc.unesco.org/heritage.htm

Frances Toronto, Canada