When you see those two big towers you first think that they are a kind of water or energy related tower, which they’re totally not, they are relics of the second world war fortifications in other word : blockhaus.
Most of the blockhaus i know or that we usually see are on the beaches half trapped in sand or under a lot of vegetation lost in fields, not bluntly scorching the eyes in the middle of a modern city where most of them have been destroyed. But here they stand as immuable reminders of the dark years of the third reich. They’re call Flak tower (flak is an acronym for some german huge defensive anti-aircraft reinforce-concrete tower).
They just begins to be re-used, one now hosts a zoological collection “The house of the sea”, we must not forgot that, primarily they were supposed, after the war, to be covered in marble and gold as memorials and reminders of the german triumph…Lucky for us they’re now in ruins !