Gatehouse of Heisterbach Abbey

The archway of the baroque gate house from 1750 is the well-preserved entrance to the monastery property.

Baroque, built in 1750, entrance to the monastery complex

The Heisterbach Monastery was a Cistercian abbey in the Siebengebirge. The Heisterbach monastery ruins are located between Oberdollendorf and Heisterbacherrott in the Heisterbach valley. At the instigation of Archbishop Philip I of Heinsberg from Cologne, the Himmerod Abbey in the Eifel sent twelve monks to found a daughter monastery in the Siebengebirge. On March 22, 1189, they first moved into the abandoned building of an Augustinian order on the Petersberg (also part of this hike).
It took until 1202 until the move to Heisterbach in the valley of St. Peter, as they called it, was completed and the foundation stone for the new monastery could be laid. From 1211 the monastery was called "Maria im Peterstal in Heisterbach". Later it was only called Heisterbach Monastery. This name is also on a coat of arms above the entrance gate.
On October 18, 1237, the new abbey church with a length of 88 meters and a width of 44 meters was consecrated. In 1327 the entire monastery complex was completed.
With the secularization, the Heisterbach Abbey was abolished in 1803. The church was sold to a French entrepreneur for demolition in 1809. The stones were used to build the north canal between Venlo and Neuss. Later they were also used for the Ehrenbreitstein Fortress near Koblenz. It was not until 1818 that further explosions were stopped by an order of the Upper President of the Rhine Province, so that the ruins of the choir could be preserved.
(Info taken from de.wikipedia.org/wiki/Kloster_Heisterbach)