Powis Castle (Welsh: Castell Powys) is a British medieval castle, fortress and grand country house near Welshpool, in Powys. The seat of the Herbert family, Earls of Powis, the castle is known for its formal gardens and for its interiors, the former having been described as "the most important", and the latter "the most magnificent", in Wales. The castle and garden are under the care of the National Trust. Powis Castle is a Grade I listed building.