Nördlingen

One of only three towns in Germany whose medieval walls remain completely intact and walkable at the top, Nördlingen sits at the centre of the Ries crater, a 25-kilometre-wide impact basin formed by a meteorite roughly 15 million years ago. Suevite — a type of impact breccia — is visible in the building stones of the town. The tower of the late-Gothic St. George's Church offers a bird's-eye view of the circular street plan and the surrounding crater rim.