Further to the right are the remains of the Norman castle. The Agricola Tower is a Grade I listed building. It is built in sandstone ashlar with a metal roof in three storeys. The ground floor has a blocked gateway and to the right of the gateway is a slightly projecting stair turret. Internally, the ground floor consists of a crypt, and the first floor contains the chapel of St Mary Castro. The Agricola Tower is also a scheduled monument. The chapel is still consecrated as the regimental chapel of the Cheshire Regiment. Its ceiling is covered with frescos dating from the early part of the 13th century which depict the Visitation and miracles performed by the Virgin Mary which were revealed during conservation work in the 1990s.