Martinsburg Castle with its powerful hexagonal tower was built around 1324 as a toll station on the Rhine bank in Oberlahnstein. It was a toll castle in the Electorate of Mainz. The pictorial assembly was built together with the town fortification.
The pointed gate in the east wall shows a delicate cast iron oriel with emblem (1395). The north wing probably contained the main rooms. The apartment tower in the northwest, built in the 14th century, was modified in the 18th century. The south wing is likewise Gothic. The archbishop Franz Lothar von Schönborn established the southwest and west wing between 1719 and 1721; there the main tower (end of the 14th century) is assembled; at its windows one sees outside small console stones for the fold-down wooden shutters. The roof dates from the 18th century.
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.