Its origins probably date back to the turn of the 16th century, when it may have served as a bastion supporting the defence of the St John’s Gate forecourt, which it adjoined. Together with the other fortifications, it was modernised by the imperial army during the Thirty Years’ War around 1630 and strengthened with a fausse-braye. Today it is 12 m high and 60 m in diameter. The site was also used by local bell founders for casting bells.
The Griffin is shown with a cannon, referring to the defensive role of the roundel and to the events of the Thirty Years’ War (1618–1648).