Vlotho was a medieval hill castle above the town with same name. The extended property is located on the Amtshausberg with a steep grade to east and south. The bent river has a natural harbour, on the medieval main road from Frankfurt to Bremen.
The castle was built around 1250. It was razed around 1368. The foundation is the only part from the medieval period. Drawings dating back to 1581 are extant, but they are no reliable representation. The castle ruins were demolished in 1709, with only the dungeon surviving until 1936. The castle ruin is c. 110 metres m long and c. 60 metres m wide. The surrounding wall is mostly preserved.
Part of the reconstructed castle is covered by a modern protective roof. The property features a restaurant with garden area. The terrace offers a view over the Weser valley.
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.