On the scree-strewn summit, at a height of 485m, of Tre'r Ceiri is one of the best preserved Iron Age hillforts in Britain where round houses, gateways and ramparts can be seen in a remarkably intact condition. Tre'r Ceiri on the slopes of Yr Eifl, or The Rivals, is accessible from a layby close to the village of Llanaelhaearn.