Work on Aberystwyth Castle commenced in 1277 under Edward I and was completed in 1289. It is a concentric-walled lozenge-plan castle of coursed rubble masonry. It has a dry moat to the west and round towers to the inner and outer wards. There is an inner gate tower to the west with an outer gate beyond. The twin aspidal tower gateway has a pointed entrance, portcullis chase, crenellated parapet and splayed stair turret. There is a dungeon to the southwest and a mural tower on the south side of the inner ward.

A Royal Mint was established by Thomas Bushell in the castle hall in 1637. Around 1790 the ground in front of the Castle was laid out in a series of walks by John Probert. The site is now partly covered by St. Michael's Church. Aerial reconnaissance in 2001 noted earthworks of parallel ridges in the western end of the castle, between the moat and the war memorial. These are possibly cultivation ridges, gardens or even allotments.

Sources: Cadw listed building description; Victorian Society tour notes, 1999

RCAHMW, February 2011