One of the oldest cities in Germany, it was established by the Romans in the first century C.E. As if that was not enough, each succeeding wave of conquerors seemed to come across this area along the Neckar and dwell a time. As a result, the wall foundations have been layered on top of each other.
With the advent of the 1200s, the churches really went into build mode. Parts of the city have survived from the 1400s with other buildings dating in the 1500s, 1600s, and 1700s. I have referred you to the German Wikipedia article as neither the English version or the city website are worth viewing. A small town, there are excellent museums and historical preservation has resulted in a wonderful look and feel. Unlike Rotenburg a. der Tauber, it is not over run with tourists.