Grevenburg castle was built in 1350 by Count Johann III of Sponheim-Starkenburg and replaced Castle Starkenburg as the residence of the Rear County of Sponheim. With the extinction of the ruling male line of the Rhenish branch of the House of Sponheim in 1437 the castle became seat of the bailiff of the new Counts to Sponheim.
In 1680 it was conquered by Louis XIV of France and was extended, together with the fort of Mont Royal in the horshoe bend of the Mosel north of the town of Traben-Trarbach as a part of the fortifications. During the War of the Spanish Succession (1701–1714), in 1702 it was taken by the French under Taillardin and in 1704 on the express orders of the commanding officer John Churchill, 1st Duke of Marlborough it was overpowered by Friedrich das Wehrschloss. The badly damaged castle was then occupied by the Dutch. In 1730 it was repaired by the Electorate of Trier for the defence of Koblenz and the Rhine river. In the War of the Polish Succession it was taken after three weeks' siege for the fourth and last time by the French who destroyed it in July 1734. The castle was blown up, huge chunks of it have plunged into the valley beneath.
Of the castle, although only the western wall of the former keep remains, the foundations are largely intact.
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.