View larger size Karl’s Gate The Hauptstrasse extends the entire length of Heidelberg’s Old Town from west to east. At its eastern end is Karl’s Gate. Architect Nicolas de Pigage built it between 1775 and 1781 in the form of a Roman triumphal arch. It was supposed to express the gratitude of the town’s residents to Prince Elector Karl Theodor for promoting trade and commerce. But while it was being built they began complaining about the horrendous cost, which was going far over budget. The sculptures by Peter Simone Lamine on the east side show the coat of arms of the Kurpfalz flanked by two lions. On the side facing toward the city, there are portraits of the Prince Elector and his wife.