Basilika Sankt Kastor

The Basilica of St. Castor, Koblenz's oldest surviving church, stands just behind the Deutsches Eck at the confluence of the Moselle and Rhine rivers. Its origins trace to the early 9th century under Carolingian rule, though the building's defining Romanesque character — twin towers, rounded arches, and vaulted nave — took shape primarily in the 12th century, with later 19th-century additions. The interior is exceptionally well preserved: carved capitals, original vaulting, and a largely intact historic furnishing make it one of the most significant Romanesque church interiors along the Middle Rhine. Listed as a protected cultural monument, it continues to function as an active Catholic parish church. The basilica's austere stone exterior offers a quiet counterpoint to the tourist bustle of the nearby Rhine embankment.