Château de Castelnoubel is situated on a promontory overlooking the Mondot valley near Bon-Encontre. The site where the castle stands has been occupied since the 10th or 11th century. Construction of the current castle began in the late 13th century. It belonged to the Marmande family initially, with Arnaud de Marmande being the first known lord. The Durfort family took ownership after the Marmandes, with Arnaud de Durfort receiving jurisdiction rights from Charles le Mauvais, King of Navarre. The Durforts continued to hold Castelnoubel until the late 16th century, when it passed through marriage to the Secondat family.
In the early 18th century, Castelnoubel came into the possession of Louis Pascault de Poléon and remained in the Pascault de Poléon family until the 19th century.Pierre Loubat and later Joseph-Marie-Étienne Giraud, who served as secretary general of the prefecture of Agen, were subsequent owners.The castle eventually became a historic monument in 1966.
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.