The oldest parts of the castle date back to the Staufer period. The remaining sparse building fabric was secured during renovation work. Valuable stove tile finds and the remains of tableware illustrate the lifestyle and domestic culture of the 13th and 16th centuries. The artefacts are on display in the Bleichheim local history museum. The castle has not been permanently inhabited since the beginning of the 16th century.
Below the Kirnburg, the remains of a predecessor castle rise up from the wooded area of the "Kastenbucks", the structures of which have recently been recognised thanks to precise measurements. In addition to a tower mound and ramparts, the foundation walls of a building measuring 10 x 20 metres can be seen.