On the foundation walls of the former Weißenfels castle, the residence of the Weißenfels dukes "Schloss Neu-Augustusburg" was built in the years 1660 to 1694 in the form of a monumental three-wing complex. The castle served as the residence of the Electoral Saxon collateral line Saxony-Weißenfels until 1746 and quickly developed into a cultural stronghold.

Johann Beer acted as ducal concertmaster at the Weißenfels court, while Johann Phillip Krieger held the post of court kapellmeister. The personal physician of the Duke of Weißenfels, Johann Adolf I, was a certain Georg Händel, who took his seven-year-old son to Weißenfels one day. Little Georg Friedrich Händel played the castle church organ so impressively in the Duke's presence that he convinced his father to provide a musical education for his son.

Thus, Weißenfels is considered the place of discovery of George Frideric Handel. Another world-class artist is also associated with Weißenfels Castle: Johann Sebastian Bach served as court chapel master here.
Opposite the Comedy Hall in the north wing is the impressive Castle Church of St. Trinitatis, which is still preserved today and is one of the most beautiful early Baroque churches in central Germany. Equipped with frescoes and magnificent stuccowork by Italian masters as well as a Förner organ, the church holds another treasure in the basement rooms: the princely crypt with magnificently decorated tin and wooden sarcophagi of the dukes of Saxony-Weißenfels.
Today, the museum in Neu-Augustusburg Castle houses an exhibition on the Duchy of Saxony-Weißenfels and the history of the town. It also houses the largest shoe museum in the new German states, with shoes from all over the world and from prominent personalities. The castle church as well as constantly changing special exhibitions can be visited during opening hours.