Olsztyn Castle (Polish: Zamek w Olsztynie) – castle ruins located in the Kraków-Częstochowa Upland, lying on the Trail of the Eagles' Nests – formerly protecting the southern border of the Kingdom of Poland.

[1][2] The castle, located on a hill, among limestone rocks, is part of the Trail of the Eagles' Nests.

[3] Taken away from him in 1396, the castle was then handed by King Władysław II Jagiełło to a local nobleman, Jan Odrowąż of Szczekociny.

The castle was invaded several times by Silesian princes in the 15th century, and with the advancement of warfare, its fortifications became obsolete.

The most impressive still standing part of the castle is a 35-metre round tower, built in the 13th century, which served as a prison.