Underground walking tour inside Petrovaradin fortress is 1km long out of 16km long network that stretches through 2/3 of the fortress.
Tunnel network is spread in four levels and the tour leads you through the first level that is 30-40 minutes long.
Tour guide explains history of the fortress and how the tunnel system would be used for defense of the fortress.
For a full refund, cancel at least 24 hours before the scheduled departure time.