Hay Castle, also known as Castell Y Gelli, stands prominently in the historic market town of Hay-on-Wye in Powys, Wales, near the English border. Originally a Norman ringwork fortress from the late 11th or early 12th century, the castle was developed significantly around 1200 when Matilda de Braose constructed its stone keep. The castle features Britain's oldest working defensive gates, with one wooden gate dating to approximately the 14th century and another from the 17th century. After centuries of decline, the Hay Castle Trust has restored the property since 2011, partly funded by over £5 million in National Lottery Heritage grants. Today it welcomes visitors with guided tours, exhibitions, a café, and serves as a vibrant centre for arts, literature and learning.