At the southern end of Llyn Padarn is the 800 acre Padarn Country Park and towering overhead is the ruin of Dolbadarn Castle.
Built sometime before 1230 by Llewellyn the Great, the purpose of the castle was to guard the route through the mountains. The tower is built of slate and contains many chambers. It has a diameter of 40 feet and walls 8 feet thick. It once rose 3 storeys high, but fell into disuse after the conquest of Wales by Edward I, who built the castle at Criccieth. It is now listed as a World Heritage Site.