The Tower was built in the 13th century by Simon (Son of Salamon) among the swamps of the Sió river. The name Simontornya means Simon's Tower. Nearly all owners of the castle made some alterations throughout the centuries. The Lackfi's built a new gothic wing in the 14th century, altered the old Tower, and added an arcaded loggia to the back-front. After the extinction of the Garai family in 1482, the castle again belonged to Queen Beatrix, wife of Matthias Corvinus. Simontornya Castle from the North side
Mózes Buzlay, marshall of King Ulászló II improved the castle into a renaissance palace with the help of Italian masters and craftsmen from Buda. After Buzlays' death the castle was taken over by the Turks in 1545. This event marked the beginning of a new era with an emphasis on military requirements. During the nearly 150 years of occupation minor alterations and refinements were constantly being made.
Simontornya, the center of a sandjak was recaptured by Louis William, Margrave of Baden-Baden in 1686. In just two years (1702-1704) major alterations turned the castle into a fortress. During the revolution against the Habsburgs, led by Prince Francis II Rákóczi, Simontornya became the stronghold of the Kuruc rebels in southwest Hungary. The fortress was captured by the Austrian army in 1709 housing troops until 1717. The castle fortress was later donated to the House of Limburg-Stirum, but, after building a new a castle, they turned the old one into a barn. It has been used as a barn by all new owners until 1960, when archeological excavations started.