Castell Dinas Brân is a medieval castle, built by the Princes of Powys Fadog, which occupies a prominent hilltop site above the town of Llangollen in Denbighshire, Wales. The presently visible stone castle was probably built in the 1260s by Gruffydd Maelor II, a prince of Powys Fadog, on the site of several earlier structures, including an Iron Age hillfort.