Teutonic Knights conquered the Ełk area in 1283. They built first a wooden castle to the site of former Old Prussian settlement and the town grew around it. It was first documented in 1398. The brick castle was built in 1497. In 1888 the castle was rebuilt - it became a prison and had that function until 1976. In 1958 during renovation of part of ther castle, under its walls, there was a collapsed tunnel found. After 1985 the castle doesn't have nor any function neither conservation care.
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.