The 900-year-old church is vintage late Romanesque, with a massive octagonal main tower and a soaring spire. It stands on a site where two Roman soldiers were executed in the 3rd century for being Christian. It saw the coronations of two Holy Roman Emperors (in 1314 and 1346) and was one of the Rhineland's most important ecclesiastical centers in the Middle Ages. The 17th-century bronze figure of St. Helen and the ornate rococo pulpit are highlights of the interior; outside
you'll find two giant stone heads: those of Cassius and Florentius, the martyred soldiers.