A castle in Arbon is first mentioned in 720 in a history of St. Gall Abbey. It stood on or near the site of the Roman era Arbor Felix fortress from 250 AD. After the Romans retreated south of the Alps around 400, the old fortress was abandoned. Sometime later a Frankish castle was built in Arbon probably for the Frankish royal family. By around 700, Arbon and presumably the castle, were the property of the diocese of Constance and an ecclesiastic overseer or bailiff ruled over Arbon.
The oldest part of the current castle is a 13th-century, originally free standing, residential tower. The tower may have been built on the foundation of an earlier building. The lower walls are up to 3.2 meters thick. Inside the castle there are two Romanesque fireplaces. In 1515-20 the Bishop Hugo von Hohenlandenberg rebuilt the castle to its current appearance. The old tower was rebuilt into a U shape. The upper most story, the gables and the hip roof are also from this reconstruction. The outer wall of the castle moved to stand exactly over the north-west corner of the Roman era fortress.
In 1822 the Stoffel silk ribbon weaving company moved into the castle. They remained there until 1907. In 1911 the castle was bought by Adolph Saurer, the founder of Adolph Saurer AG. He built workshops around the castle building as he experimented with motors, trucks and machinery. In 1944 his son, Hippolyt Saurer sold the castle to the city. The city renovated and expanded the castle and in 1967 opened the Historisches Museum Arbon (Arbon History Museum).
References:The Jan Hus Memorial stands at one end of Old Town Square. The huge monument depicts victorious Hussite warriors and Protestants who were forced into exile 200 years after Hus, and a young mother who symbolises national rebirth. The monument was so large that the sculptor designed and built his own villa and studio where the work could be carried out. It was unveiled in 1915 to commemorate the 500th anniversary of Jan Hus' martyrdom. The memorial was designed by Ladislav Šaloun and paid for solely by public donations.
Born in 1369, Hus became an influential religious thinker, philosopher, and reformer in Prague. He was a key predecessor to the Protestant movement of the sixteenth century. In his works he criticized religious moral decay of the Catholic Church. Accordingly, the Czech patriot Hus believed that mass should be given in the vernacular, or local language, rather than in Latin. He was inspired by the teachings of John Wycliffe.