The architect was John (de) Helpston who had also designed castles for King Edward II in North Wales.

Its prime purpose was to defend the port of Chester, and it was also used to monitor the movements of shipping and to ensure that the custom dues were paid.

[3] In 1639 the tower was renovated at the city's expense and during the following decade embrasures in the spur wall were made into gun ports.

The tower closed as a museum in 1901–02 while the city walls were rebuilt, and re-opened in 1903, attracting 12,000 visitors that season.

[1] The tower is circular at its base with a square turret above, in two stages containing octagonal chambers, one above the other.

Five stone steps lead down from the archway through the wall (about 12 feet (4 m) thick) to the lower chamber.

A circular staircase of 23 steps leads to the upper chamber, which has four embrasures in its walls.