Neuchâtel castle adjoins the collegiate church and overlooks the city. By following the circular path at the base of the outer walls, you get a general idea of the different parts of the building erected around a large courtyard and a smaller one, to the south. It can be accessed from Rue de la Collégiale or the cloisters.
The castle history dates back to the Roman age, but the first stone castle was probably built in the 11th or 12th century. It has been altered and rebuilt several times. From 1708 to 1848 it belonged to the Prussia.
The construction of the church began at the end of the 12th century and was completed in 1276. Facing the gates of the castle, the three apses are striking by the beauty of their Roman design. Only the south clock tower is ancient, the spire and the north tower being built in 1869.
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.