Construction of the Porrentruy castle took place between the mid-13th century and the beginning of the 18th century. The oldest part is the thirteenth century Réfous Tower. 14th century ramparts survive on the western and northern sides.
During the reign of Prince-Bishop Jacob-Christoph Blarer of Wartensee, the castle underwent an extensive period of reconstruction by the architect Nicolas Frick around 1588. In 1697, it suffered a huge fire. The courtyard is enclosed to the south by the long Princess Christina Wing, which was named in memory of visits made by Christina of Saxony, the aunt of Louis XVI and Abbess of Remiremont from 1773 to 1775.
Since 1271 belonging to the bishopric of Basel, the castle served as exile residence of the prince-bishops of Basel from 1527 until 1792. The bishops had been exiled from Basel during the Swiss Reformation in 1529, whereas they were able to keep most of their territories outside the city.
Today, the castle is the seat of the judicial authorities of the Republic and Canton of the Jura. The building’s interior is not open to the public at weekends.
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.