Leichtweiß Cave, located in the rear Nero Valley, was formed millions of years ago in the middle Palaeozoic era by the Variscan folding of the mountains and the erosive force of the Schwarzbach stream. It was first mentioned in 1791, when forest workers sighted rising smoke and discovered the small cave in which the poacher Heinrich Anton Leichtweiß had hidden. After that, the hideout fell into oblivion again. With the rise of Wiesbaden as a fashionable spa town, the cave once again came to the attention of the public and was recommended in literature as an excursion destination as early as 1825.

In the search for ever new attractions for the steadily growing number of out-of-town visitors to Wiesbaden, the cave in the Nero Valley was finally discovered. At that time, stories of robbers were on everyone's lips and the "Schinderhannes on the left bank of the Rhine" was known far beyond the region. In no time at all, the game thief Leichtweiß was turned into the "robber chief" Leichtweiß and his temporary hideout was converted into a wildly romantic robber's cave approx. 30 m long and approx. 2 m high by the Wiesbaden Beautification Association in 1856. In addition to a second entrance to the north and a niche padded with moss and accessible via a wooden ladder as a sleeping area, a round room was created at the side with a stone table (with a hollow table base for the "loot") in the middle and benches along the walls. Other furnishings included old firearms, sabres and pictures of the "robber" and his "lover". The entrance to the cave and the surrounding area were romantically designed in keeping with the tastes of the time with an artificial waterfall, wooden bridge, railings made of branches, a viewing temple and a shelter for the warden.

After the Second World War, things went increasingly downhill for the Leichtweißhöhle. As a result of neglect and vandalism, the outdoor facilities gradually disappeared, the warden was beaten up several times and the cave was misused as a shelter. The result was its closure. In 1983, the city put an end to the cave's slumber and rebuilt the entrance, which had been repeatedly broken into, with concrete and a steel door; it has been open regularly ever since.