Some people chase peaks, others follow lakes. In Wales, the Snowdonia (Eryri) National Park is one stop that quietly combines both—Dolbadarn Castle. Standing beside the serene waters of Llyn Padarn, this 13th-century fortress was built by Llywelyn the Great—Prince of Gwynedd from 1199 to 1240—to guard the route through Llanberis Pass. Built from purple and green slate, the castle was largely assembled using dry stone techniques without mortar, apart from the keep. Its distinctive round tower once stood watch over the valley. History here has its twists. Owain Goch ap Gruffudd, Llywelyn's nephew, is believed to have been imprisoned inside these walls after a family feud.

Today the fortress is a peaceful ruin, but the setting still steals the show. During this annual initiative, Dolbadarn reminds visitors that some places are built to last—and others are simply built to be discovered.