The first castle in Xaintrailles is mentioned in 1259 as being held by three co-lords, all from the Xaintrailles family. It was built in the early 13th century, and what remains are the medieval outer courtyard, the keep, and the embankments of the south and west walls.
Jean Poton de Xaintrailles, a companion of Joan of Arc who died in 1461, followed by his successors Bernard de Lamothe and Antoine de Chamborel, governors of Casteljaloux, undertook constructions in the 15th century: two towers and the north residential wing. In the 16th century, turrets with fan-shaped projections were added to the south elevation, and moats and a drawbridge are mentioned in 1539. In 1570, the castle passed to the Montesquiou family, and later through marriage to the Lau de Lusignan family in 1724.
Around 1780, Armand de Lau, Marquis de Lusignan, had the moats filled in and an access arranged from the west. In 1824, the northeast rooms collapsed, and in 1843, the keep was partially restored based on the project of Gustave Bourières, the department's architect.
The oldest part of the castle is the 13th-century keep, with windows added in the 15th century. The north residential wing from the 15th century has one square floor and two attic floors with a hipped roof covered with flat tiles. Like the keep, it has an out-of-service staircase. The one-story and attic south building with turrets was renovated (kitchens). The west wing is flanked by two towers.
The U-shaped staircase and vestibule were added in the 18th century.
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.