Sitting atop a sheer cliff just east of Slea Head, outside the village of Ventry, this 5th-century fort’s stony walls rise from the cliff edge as if they were always part of it. The round Iron Age structure’s stone walls are still mostly sturdy, although part of the fort tragically fell into the sea during the floods of 2014. Walk around the fort to see where other fortifications and “beehive” huts were built inside the walls thousands of years ago. There’s also a mysterious underground passage. (At the time this book was being written, the fort was viewable only from the outside, due to storm damage. Call ahead for a repair schedule.)