It was erected in the north-west of the town, within the walled enclosure. It had a parade ground where eight to ten thousand men trained, and was surrounded by a strong wall with 18 towers. More than half of the original construction’s wall remains, and approximately 76 x 47 m of the enclosure’s floor can be determined. The walls is approximately 2.60 m thick. Two of the towers are recognisable, and we can determine the location of two others: at the sides of the enclosure’s current entrance way. The keep half protrudes from the centre of this wall. It is almost square in shape and is around 20 m tall. Almost 11 m from current ground level is a octagonal-shaped chamber with cloister vault, with squinches in the angles. The other preserved tower is found in the north-east corner. It is approximately 10 m high and has a square floor and the corner that faces the interior of the enclosure is bevelled. The las Escolapias convent-school is currently housed within the enclosure.