21 Jun Dun Aengus , Aran Islands
A fantastic Prehistoric stone fort.
Dramatrcally sited above a two-hundred-foot cliff on Inishmore (Aran Island), Dun Aengus has multiple walls, the innermost one defended by stone snakes known as chevaux-de-frise.
The date of construction is uncertain, but recent excavation showed human activity in interior from about 800 B.C. onward.
Tours of Ireland will reveal great prehistoric attractions.