Prussia still exists, in Birmingham!?

It's 1736 in the Prussian city of Königsberg, now the Russian exclave of Kaliningrad, and Leonhard Euler, probably the greatest mathematician of the 2nd Millennium, is on a jog or something and decides to try to cross every one of the seven bridges over the river Pregel once and only once to prove his worth as a nerd. He failed. And subsequently he went home and drew up a snazzy mathematical proof as an excuse.

Oberwölz: A Wayfarer's Guide

I mounted the shoulder of the ridge and pulled up, raising my visor to get a good look at the valley before me. The river ran down the middle of the basin that lay before me, carving it’s path around and back to the sea that I had started at so many weeks ago. The walled town of Oberwoelz sat upon the river, some three leagues from my current position; just as my map read. I saddled back up and completed the final leg to my next country of destination.