Ulm

Ulm needs 1 day: Ulm Minster, with the tallest church steeple in the world (161.5 meters, climbable for those unafraid of 768 steps), is the main reason to visit. April-October is best. It's mid-priced by German standards. It's Albert Einstein's birthplace, and its minster, though never a bishop's seat, surpassed every Gothic cathedral in Europe in height thanks to a construction project that stretched, with interruptions, over more than 500 years.