This is now a restaurant, offering superb views across the river.
It was the former Bastion in Cologne, to take a closer look, walk down the steps from the main road onto the waterfront and look up, I thought that this building was really interesting...I loved the way in which the top part sticks right out across the walkway!
This former bastion is now a restaurant with a nice view over the river Rhine.
Unfortunately, it is now closed. I took the photo as I went past it on a river boat cruise. But I also included it on one of the walking tours I took.