Twelve Romanesque churches of Cologne

The reason for the large number of churches was that in the Middle Ages Cologne was, along with Paris, the largest and most important city north of the Alps, and both were already important centers in Roman antiquity (Cologne's name was Colonia Claudia Ara Agrippinensium, the provincial capital of Germania Inferior).

Christianity also has a long tradition in both cities; the first bishop of Paris was the missionary Dionysius of Paris (around 250), the first bishop of Cologne was Maternus of Cologne (c. 285-315 AD), a close confidant of Roman Emperor Constantine the Great.

The graves of two important women can be viewed in the churches: of Plectrude (died 718), the founder of the church St. Maria im Kapitol, and, in St. Pantaleon, of Empress Theophanu (died 991), a Byzantine princess who ruled the Holy Roman Empire forcefully and capably as dowager empress for her minor son.

With the exception of St. Maria Lyskirchen all of these churches were very badly damaged during World War II.

A 13th Romanesque church, St. Maria ad Gradus, which can be seen on a plan from 1571 and in later pictures, had already been demolished in 1817; she stood directly in front of the Cathedral choir.