View of the Old Tiefental Bridge

The Forggensee is a reservoir. In winter, when the water is drained, it becomes a lunar landscape - then you can see the remains of the Roman Via Claudia Augusta or the remains of a sunken city

In 1954 two Lech barrages were completed at Schwangau and Roßhaupten and the valley bottom flooded. The reservoir was intended as a flood retention basin for the downstream communities and as a guarantee for an even power generation by hydropower. The houses and courtyards in the valley were sacrificed for this "progress", and this despite the fact that some residents fiercely resisted. Today, many people no longer even know that the lake owes its name to the sunken hamlet of Forggen.
It is only really full of water between the 1st of June and the 15th of October. Over the winter he is gradually drained and releases a large part of the valley floor again. And then you can search for the remnants of the sunken world.
Source: tief-im-allgaeu.de/unddeckungsreise-auf-dem-grund-des-forggensees
And so, too, the old Tiefental Bridge comes to light again and again, around which or its predecessors a legend is entwined.

You can rarely stand on the bridge. If possible you should take advantage of it. The last time it was possible in 2018.