Tower of Vrdnik, Medieval tower in Vrdnik, Serbia.

The Tower of Vrdnik is the surviving keep of the fortified town of Vrdnik, standing on the southern slopes of Fruška gora at 383 metres. The roughly cylindrical stone tower rises 18.5 metres, with a slightly flared base, a small rectangular opening halfway up, and a broken, uneven top with a large V-shaped gap. Only fragments of the walls and the ruin of one other tower remain.

The fortified town of Vrdnik is first mentioned in written sources in 1315. Finds from the site, including objects from the reign of Roman emperor Probus (276–282), who governed part of the empire from Sirmium, suggest an earlier watchtower or outpost here. Of the medieval town only the donjon tower, fragments of walls and the ruin of one tower remain.

The tower's Hungarian names, Rednak and Rednuk, survive alongside the Serbian Vrdnička kula, a trace of the region's changing rulers. It is a protected cultural monument of great importance, and the wooded slope around it is now walked by hikers on the half-hour trail up from Vrdnik.

The tower is reached via a marked mountain path that winds through surrounding forest and involves a steady climb. Wearing sturdy shoes and allowing time for the hike are important since the trail goes through woodlands.

The tower is 18.5 metres high and stands at 383 metres above sea level, about half an hour's walk north of Vrdnik. Finds from the reign of Emperor Probus (276–282), who ruled part of the Roman Empire from Sirmium, suggest the first fort here was a watchpost for Sirmium. No archaeological, architectural or historical research has yet been carried out, though a survey base of the fort has been made.