This circular building was erected in 1499 as a defence against the Ottoman threat, designed to act as an outpost before the city's ramparts and moats. Today it is isolated in the midst of Planty Park, but it was originally linked to the main gate of St Florian's by a covered passageway. A rare example of a perfectly conserved barbican in Europe, its high walls are dotted with an impressive series of machicolations and arrow-shooting slits.