The ruins of the 14th-century Olsztyn castle are one of the biggest attractions of the area. The castle, located on a hill, among limestone rocks, is part of the Trail of the Eagles' Nests. It belonged to a system of fortifications, built by King Kazimierz Wielki, to protect western Lesser Poland from Czechs, to whom Silesia belonged at that time. For some time, as a fee, it belonged to Prince Wladyslaw Opolczyk. Taken away from him in 1396, the castle was then handed by King Wladyslaw Jagello 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. In 1655, it was captured by the Swedes, and since then, it became a ruin. In 1722, it was partly demolished, with bricks used to build a parish church at Olsztyn. Currently, only fragments of defensive walls remain. The most impressive still standing part of the castle is a 35-meter round tower, built in the 13th century, which served as a prison.
References:The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.