Overlooking Schmalkalden, the late-Renaissance Schloss Wilhelmsburg was built between 1585 and 1590 by Landgrave Wilhelm IV of Hessen as a hunting lodge and summer residence. Since then, it has largely kept its original design, with lavish murals and stucco decorating most rooms, of which the Riesensaal, with its coffered and painted ceiling, and the Festsaal are the most impressive. The playfully decorated Schlosskirche has a rare wooden organ, thought to be the oldest working organ of its type in Europe.
In addition to temporary displays, the Schloss Museum houses a permanent exhibition on the Schmalkaldic League, a military alliance of Protestant territories formed in 1531 to prevent the re-imposition of Catholicism. Laid out in the early-17th century, the palace grounds retain much of their original design, the perfect setting for what is considered one of the best-preserved Renaissance palace exteriors in Europe.