The city history of Fresnay-sur-Sarthe really begins with the erection of the castle, which was initiated approximately in the 10th century (perhaps in the 9th century), under the reign of Charles the Bald. The purpose of the castle was mostly to ensure protection of the river crossing.
William the Conqueror captured the castle twice; first in 1063, then again in 1073. Young Robert of Bellême, who particularly distinguished himself during the siege, was proclaimed as a knight from William's hand.
The strategic importance of the Castle of Fresnay was particularly highlighted during the Hundred Years' War. Successively occupied by the adventurers of Philippe de la Chèze, in 1356, then captured by the English troops of King Henry V, in 1417, it came back to the French, thanks to Ambroise de Loré, future companion of Joan of Arc; Captain of the Castle in 1418, he later became 'Prévôt' de Paris.
In 1420, the city was again taken by the English who occupied the place for thirty years (1420 to 1450). Heavily affected by the Hundred Years' War, Fresnay also had to suffer from the Wars of Religion; in 1562, it was devastated by the Huguenots. From then, the castle started to gradually fall into ruins.
By the late-17th century all that was left of the castle was its gate house, a salt house, the bases of the curtain walls and a ruined keep. It was then donated by Louis XIV of France to the town to serve as a prison and court.
At present the grounds of Fresnay-sur-Sarthe Castle are a nice public park and it is freely accessible. The salt house is now a small local museum.
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.