The grandiose architectural legacy of its history today includes impressive eight UNESCO World Heritage Sites. This includes the landmark of the city: the Porta Nigra (180 BC), one of the best-preserved Roman city gates north of the Alps. The huge sandstone blocks weigh up to 6 tons! The fantastic basilica with the throne hall of Emperor Constantine. The amphitheater, scene of gruesome gladiator battles and bloodthirsty battles between humans and animals. Finally, the Imperial Baths, which were among the largest baths of the Roman Empire. The old Roman bridge, probably the oldest bridge in our country. The cathedral with the world-famous relic, the "Holy Rock" and the Liebfrauenkirche, the oldest gothic church in Germany. The Electoral Palace is considered one of the most beautiful Rococo palaces in Europe.