In the 1980s, the river Nahe was covered over with a four-lane highway, Bundesstraße 41, mentioned above, putting the river underground, beneath the town.
This is unique in Germany and has greatly changed the town's appearance in this area.
The first plans for this development (officially the Nahehochstraße) lay before planners as early as 1958, but they set off a wave of criticism that was felt far beyond the town's limits.
On the theme of “Highway over the Nahe – yes or no”, Südwestfunk broadcast a talk show in the 1980s.
The project was meant to relieve traffic congestion in the inner town on the B 41, which at the time ran through what is now a narrow pedestrian precinct through the middle of the Old Town.
Work on the project began in 1980, and lasted five years, after which the Nahehochstraße was at last completed.
The Nahe had thus been channelled into a two-kilometre-long tunnel.
A timber-frame house nearby, the Sachsenhaus, was torn down and put into storage, its pieces numbered.
Its reconstruction has been indefinitely postponed.
In 1986, the Naheüberbauung, as it is commonly known, was opened to traffic.
For its 20th anniversary, there was an exhibition at the Idar-Oberstein Stadthaus (civic centre) with photo galleries about the planning, building and completion of the project.

For its efforts, Idar-Oberstein won an award in 1988 in a contest staged by German town planners: First Prize for Most Consequential Blighting of an Historic Townscape.
In the 1980s, the river Nahe was covered over with a four-lane highway, Bundesstraße 41, mentioned above, putting the river underground, beneath the town. This is unique in Germany and has greatly changed the town's appearance in this area. The first plans for this development (officially the Nahehochstraße) lay before planners as early as 1958, but they set off a wave of criticism that was felt far beyond the town's limits. On the theme of “Highway over the Nahe – yes or no”, Südwestfunk broadcast a talk show in the 1980s. The project was meant to relieve traffic congestion in the inner town on the B 41, which at the time ran through what is now a narrow pedestrian precinct through the middle of the Old Town. Work on the project began in 1980, and lasted five years, after which the Nahehochstraße was at last completed. The Nahe had thus been channelled into a two-kilometre-long tunnel. A timber-frame house nearby, the Sachsenhaus, was torn down and put into storage, its pieces numbered. Its reconstruction has been indefinitely postponed. In 1986, the Naheüberbauung, as it is commonly known, was opened to traffic. For its 20th anniversary, there was an exhibition at the Idar-Oberstein Stadthaus (civic centre) with photo galleries about the planning, building and completion of the project.
For its efforts, Idar-Oberstein won an award in 1988 in a contest staged by German town planners: First Prize for Most Consequential Blighting of an Historic Townscape.
Idar-Oberstein