This free imperial city on the Danube is one of the most beautiful cities in Germany. Churches, Geschlechtertürmer (family towers) and medieval mansions dominate the cityscape, which none the less does not come across as museum-like due to a rich cultural life and an aspiring university. Founded as a Roman army court, the Episcopal city flourished in the 12th and 13th centuries and became the most populous city in southern Germany. Of the more than 1,500 declared heritage buildings nearly 1,000 are in the historic center which has been proclaimed a World Heritage Site by UNESCO. Regensburg is the town with the largest medieval city center north of the Alps.