If you mix medieval architecture, a dash of the feudalistic feel, and some intense trust in man-made barriers, you got Attack on Titan.
Their main idea was ok: we have murdering giants that look quite fearsome and are, well, murdering our people, let’s build walls for protection! Because of this, over a century before, three walls were erected. The outermost wall is called Maria, the wall in the middle is called Rose and the innermost wall is called Sina. They make three circles within themselves, they’re pretty close to perfectly centered. As you can probably imagine, the rich and the nobles set up camp in Sina the innermost wall and the poor stay inside of Maria.
These three walls are loved by their inhabitants, in fact, so much so that they have an entire religion dedicated to them!
So yeah, these walls are a big deal and there are some creepy close up shots of some church leaders of the walls telling people of the greatness of the walls. It has the intense look that comes from true insanity.
Anyways, these three walls are keeping people safe and are patched up by their military forces which I will address next!