Unteres Schloss, Heritage castle in Alfdorf, Germany.

Unteres Schloss is a three-story stone building with a stepped gable, located at the southeastern end of Alfdorf on Untere Schlossstraße. Two oriels project about three meters from the courtyard-facing side and end at the roofline, while a rectangular oriel with a tent roof, once likely a privy, sits between the ground and first floors on the garden side. Service buildings to the west and north enclose a courtyard, and an almost square gatehouse built in 1720 adjoins them to the east.

Built in 1550, the castle was acquired in 1628 by Georg Friedrich vom Holtz. Between 1686 and 1688 it was rebuilt under the direction of Sebastian Vogt. As late as the mid-19th century, it remained the main residence of the vom Holtz family.

The castle served as a center for craft work and farming activities, with outbuildings still surrounding the main structure today. The vom Holtz family shaped the property across generations and continues to live here, giving it the character of a lived-in historical residence.

The castle is privately owned and not open to the public, so visitors must respect property boundaries and access restrictions. From outside the grounds, the architecture of the main building and surrounding structures can be viewed from the property edge, providing adequate views of the historic complex.

The former Lust- und Glashaus at the edge of the castle garden was rebuilt in 1814 and converted into a brewery in 1834; a greenhouse was added in 1846 and 1847, and the eastern part was extended in 1972.