Altensteig Castle probably dates back to the 12th century. In 1287, the castle was first mentioned as being owned by the Counts of Hohenberg. Hermann, son of Margrave Rudolf of Baden, conquered the town but had to return it to Count Burkhard von Hohenberg in 1288. In 1398, the Hohenbergers sold the Lordship of Altensteig to the Margraves of Baden. The castle became the seat of the Baden bailiffs.
In 1603, as part of a territorial exchange, Altensteig came under the rule of the Duchy of Württemberg. From 1605, Heinrich Schickhardt built the New Castle as the administrative and residential seat of the Württemberg bailiffs. The old castle served as a grain silo from the 18th century onwards. The lower part of the striking residential tower, with a floor area of about 11 meters by 16 meters, is made of sandstone masonry. The construction suggests that it was built in the 12th and 13th centuries. Presumably, an Alemannic timber-framed building was added to it in the 15th century. The six floors housed cellars, the great hall, kitchen, living quarters, and servant quarters. The largest room, now called the 'Knight's Hall,' is located on the second floor.
On the north side, the castle complex was protected by a wall with a battlement and two towers. The towers once served as a prison. While the western tower, called the 'Heaven' tower, had barred windows that looked out to the outside, the eastern tower, called the 'Hell' tower, had a 15-meter deep dungeon. The fortifications were connected to the city wall.
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.