Lower Danube Tower (Fort XXV)

A beautiful place here on the Danube. It's worth walking along the bank.
You can't see much of Work XXIV (Lower Danube Bastion) here. From there, a connecting wall led to the Danube Tower (Work XXV), which is now home to a youth club and from which an iron chain was to be stretched across the Danube in an emergency. atarimuseum.de/festung/ul25.html (you can click through all the works using the link).
You can also see the Lower Town Throat (Work XXVI), which had to make way for the hotel in part. "When the Hotel Maritim and the Congress Center were built in the 1990s, the wall was shortened and the gate and casemate demolished."

The photo is of the Lower Danube Tower (Werk XXV) on the banks of the Valkenburg. The gun tower, called the "Red Tower" because of the material it is made of, is now used by the Youth and Culture Platform Donauturm eV, a volunteer-run youth club.

Here the Danube was secured by the federal fortress.