The foundation for Lohr Castle, first mentioned in records in 1389, was laid around 1340 by Count Gerhard V of Rieneck at the northwest corner of the old town of Lohr am Main. Initially, it was just a residential tower modeled after Flemish designs, which was surrounded by a moat and a ring wall from the late 15th century onwards. Nearby were buildings such as the bandhouse, forestry office, coach house, and cellar.
After the death of the last Count of Rieneck, Philipp III, the Electors of Mainz took over the building in 1559 as regional rulers and gradually gave it its present form. It became the seat of the Electorate's senior officials. The most well-known official was Philipp Christoph von und zu Erthal, who used the castle as his residence from his appointment in 1719 until his death in 1748. His two princely sons, Friedrich Karl Joseph von Erthal, one of the last Electors of Mainz and Prince-Bishop of the Diocese of Worms, and Franz Ludwig von Erthal, born in Lohr and later Prince-Bishop of Bamberg and Würzburg, were raised here.
In 1814, the Kingdom of Bavaria took over the castle and used it as an administrative seat. Among other things, it housed the district office of the Lohr district until the territorial reform of 1972. The building was renovated in 1913.
In the castle's Knight's Hall, the Lohr Museum of Local History and the Spessart Museum were established in 1936. The museum was closed in 1942 and reopened in 1949. Since 1972, only the Spessart Museum remains in the building, focusing on the history of the castle and the Spessart region, with an emphasis on the relationship between people and the forest.
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.