Wilhelmsburg Castle stands above the town and is its outstanding landmark. It was built as a secondary residence by the Hessian landgrave Wilhelm IV in the late 16th century and officially completed in 1590. This very well-preserved castle is one of Germany’s major monuments of Renaissance architecture. The four-wing building looks rather plain from the outside but boasts rich wall paintings and stucco work inside. The interesting original rooms include the Landgrave’s chamber on the ground floor, a number of richly decorated ballrooms, the royal chamber with a collection of cast iron stove plates and stoves from the Renaissance period to Art Nouveau and the cellar vaults, which represent an exact copy of the vaults in the Hessenhof in Schmalkalden with 13th century wall paintings illustrating the Iwein epic based on Hartmann von Aue.
Another highlight of the Wilhelmsburg Castle complex is the organ in the castle chapel. This more than four-hundred year old instrument (built in 1589) is one of the oldest organs with wood pipes in the whole of Europe that can still be played today
The Castle Museum with the permanent exhibition “Launch into a New Era” takes you back to the time of the Renaissance and the Reformation and its exhibits include a presentation of Schmalkalden and the region in the 16th century.
Church weddings can be held in the Castle Chapel and marriages in the Landgrave's Chamber.