The Basilica of St. Castor indeed holds a venerable place in Koblenz, known for its extensive Romanesque construction and traditional furnishings. It stands near the confluence of the Rhine and Moselle rivers, a location steeped in history. It has been a witness to many pivotal events, including the negotiations leading to the Treaty of Verdun in 843, which shaped the future of Europe. The basilica's Kastorbrunnen, a fountain built during Napoleon's Russian campaign, adds to its historical significance.