Petrovaradin Fortress dominates the right bank of the Danube, an enormous star-shaped bastion that the Habsburgs spent the best part of a century building. Designed by French military engineers to repel the Ottomans, it never fell to an attacker after its main construction was complete in 1780. Today it is a quiet sprawl of ramparts, courtyards, and tunnels — the centrepiece is the iconic clock tower with its reversed hands, visible from across the river.
A network of underground tunnels runs for sixteen kilometres beneath the upper fortress. Guided tours go through a section of them, including powder magazines, gun positions, and counter-mine chambers — the cool tunnels make a good escape in summer. Above ground, the upper terrace houses artists' studios and a few bars and restaurants, with one of the best views in Serbia at sunset.
Each July the fortress hosts EXIT, drawing more than 200,000 visitors to a sprawl of stages laid out across the bastions and the dry moats.