The "house without a roof", as it is officially called, is a cave dwelling that is still in use in the Upper Palatinate town of Kallmünz. The cave dwelling is located north of the Vils at the southern end of the Schlossberg, on which the Kallmünz castle ruins stand. The entrance is set back from Vilsgasse at the foot of a 20-meter-high limestone wall of the Schlossberg, and access leads between the listed residential buildings at Vilsgasse 26 and Vilsgasse 28.
The house consists of a natural cave in the dolomite rock, the opening of which is closed off by a plastered wall with a door and windows. Inside there is a hallway, a living room, two storage rooms fitted into rock niches and a historic smokehouse.
The oldest known mention of the cave dwelling can be found in a document kept in the land registry archive in Amberg with the year 1707. In the 19th century it was also known as the "house under the rock". In 1908 it was sold to the owner of the blacksmith's shop across the street, and it remains in his family's possession. The last permanent resident left the house in 1937 because he had developed rheumatism due to the damp cave air.