The cylindrical shape of the tower suggests that it was built in the 13th century.

The arrow slit openings, or embrasures, with a gun loop at the bottom indicate that the tower was modified in the 15th or 16th century to facilitate artillery operations.

The tower does not have any windows on the city side; it was built solely as a defensive structure without a secondary use as a dwelling.

The Close Gate once stood on the western side of the tower, where the road now runs.

The gate was demolished in the eighteenth century by Bullocks Wyse of the Manor of St. John to facilitate easier access to his estate.