Impressive Narrowness
One of the most curious buildings on the Middle Rhine is the so-called city wall house. The baroque half-timbered house was built around the year 1700 in front of two arches of the city wall of Oberlahnstein, and its rooms cleverly utilize the arch niches of the medieval fortification wall. With only 42 square meters of living space over two floors, it is, in the truest sense of the word, a "gem" of Lahnstein.

It is traditionally said that it served as an inn for the gatekeeper of the livestock gate, which is recalled by the painting on the front. In 1826, Josef Gärtner inherited the house "An der Mauer". In 1897, it was occupied by an eleven-member family.

The house has a kitchen and a living room on the ground floor, while upstairs there are a children's bedroom and a parents' bedroom. Furthermore, there is a cellar and two attic floors, the uppermost of which is connected to the walk along the city wall. At the northern end of the walkway, there used to be a balcony-like sitting area that was destroyed by a bomb hit in November 1944.
After the last resident moved out in 1969, the city wall house barely escaped demolition. Instead, it came into the possession of the city of Lahnstein. The quirky building was extensively renovated and prepared as an annex of the city museum to resemble how it might have looked 100 years ago. Today, the building is considered a cultural monument and can be visited as part of the historical city tour and during events organized by the support group.

Next to the city wall house stands one of the last of the numerous water pumps that used to be available, which served the drinking water supply of the city in the early 19th century. It is a cast iron pump with wrought iron decorations. The cast iron trough is an early testament to the Gründerzeit iron foundry at the foot of Ruppertsklamm.