This is the late artist M. C. Escher:
And this is one of his lithographs, from 1955, entitled Convex and Concave:
If you think this complicated and impossible, and if you worry whether seeing something like this in real life could make your brain explode . . . then AT ALL COSTS you should avoid the cathedral Notre-Dame-de-Vaux, located in Chalons-en-Champagne, France:
Why should you avoid this? Because if Escher confuses you, then the inside of this cathedral will make your head explode!
There are plenty of old cathedrals in Europe, but this one is special. It’s on the UNESCO list of world heritage sites. I never took any photographs of the inside . . . but believe me, it has a complexity of architecture that would put Mr. Escher to shame!