Too beautiful, too beautiful The Heidelberg Ancient Bridge is an old bridge with nine arches. It is the first stone bridge for Heidelberg to cross the Neckar River. It was built by Elector Karl Theodor in 1786 ─ 1788. The Neckar R. is one of the three tributaries of the Rhine River. On the left bank of the river, there are solid entrances to the bridge, and there are two round towers at the bridge, which escort the entrance to the city, which was originally a dark cell.