Simontornya Castle, 13th-century Renaissance castle in Simontornya, Hungary

Simontornya Castle is a Renaissance monument and the main sight of Simontornya, begun in the 1270s when Simon, son of Salamon of the Döröcske kindred, built a Gothic tower on an island rising from the marshes of the Sió. That tower, which gave the castle and later the town its name, no longer stands. The surviving building is a palace complex: on the south side a gate tower, old tower and staircase block were raised from their foundations after 1508, the old palace wing was given an extra storey and a full-length arcaded loggia, and the north wing holds a late-Gothic castle chapel. The outer ring of buttressed walls with a parapet-walk survives in very ruined condition.

The main structure was commissioned in 1277 by a member of the Dorrocske family named Simon. During the 16th century, the site went through major Renaissance changes that significantly altered its appearance.

The name Simontornya means "Simon's Tower", after Simon, son of Salamon of the Döröcske kindred, who built the original tower in the 1270s. The castle later served as a barn for its owners until 1960, when archaeological excavations began.

The castle stands at the northern edge of the Tolna hills, where the Sió once wound through a wide marshy valley; the medieval core was built on an island rising from that floodplain. The town is reached by fast train on the Pécs line from Budapest, by car on route 61, or via routes 63 and 64 from the M7 motorway. The remains of the outer ring wall around the early castle are still visible, though in a very worn state.

The castle's name comes from Simon, son of Salamon of the Döröcske clan, who built its original tower in the 1270s; the tower that gave the site its name no longer stands. By 1565–1570 the Ottoman garrison had been cut to 125 men, down from 191 in the early occupation years.