Tenczyn Castle, also known as "Tęczyn Castle", is a medieval castle in the village of Rudno in the Polish Jura, Poland. It was built as a seat of the powerful Tęczyński family. The castle fell into disrepair during the Deluge in mid-17th century, after being pillaged and burned by Swedish-Brandenburgian forces looking for the Polish Crown Jewels and rumored treasures of the Tęczyński family. Subsequently rebuilt, it again fell into disrepair after a major fire in the mid-18th century and remains in that state to this day.