The imposing main walls and their four towers of Yverdon-les-Bains castle follow the geometric characteristics used for lowland castles. It was planned out between 1260-1270 by the young mason and architect James of St. George. He would later travel to England where he would become the master castle builder for King Edward I. James would be responsible for building a series of castles (known as the 'Iron Ring') in North Wales following its conquest by the English Crown.
Yverdon's castle used to be the residence of the castellans of the Savoy dynasty, until 1536, followed by the bailiffs of Bern state. In 1798, the Département du Léman became the castle's owner. The Département had been set up by the short-lived Helvetic Republic (1798–1803), imposed by Napoleon I.
A few years later, Yverdon acquired the castle, to entrust it to Johann Heinrich Pestalozzi and his institute. After 1838, the castle housed a public school. New classrooms were created, especially on the second floor: dividing walls were erected, additional windows changed the severe look of the castle's façade. After 1950, these classrooms were gradually abandoned; the last classes left in 1974. The original medieval structure was then restored. The castle is today a multi-purpose cultural centre, housing a regional museum, a theatre, various conference rooms and the oldest public library of French-speaking Switzerland, founded already in 1763. The library is now part of the castle museum, existing since 1830.
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.