Europe is a dangerous place.
Okay, no, it isn't.
But it used to be.
And back then we had to be on guard (title pun!) so everyone could be safe. More or less. Or something like that...
When the Second World War raged all over the place, towers were built in Vienna - as well as other places - to better defend the city. They are called Flaktürme (the singular noun being Flakturm) and they still stand. You can find the one from the picture below close to the shopping mile Mariahilfer Straße and today it houses the Haus des Meeres, our aquarium.
The towers are all of different heights, because of their different locations in the city. But all of their topmost platforms are at the exact same altitude above sea level.
On a related but less cruel note, there's yet another - very interesting - kind of tower in Vienna. On the university's campus grounds in Altes AKH, which used to be the general hospital before a new more modern one was built and thew put students instead of patients into the former one, you'll find the so-called Narrenturm. The fools' tower.
It was built in the year 1784 as an asylum for, well, mentally extraordinary people. You get my drift, right? Thus, it was first of its kind in the whole world.
Oh yeah, we can definitely be proud of that one...
Idea: Unnützes WienWissen