This, the oldest monument in Maastricht, was already in existence in the year 1000. The high front extension dates from the same era, while the nave and apse are from the 12C. Inside the church, note the remarkable chancel comprising two rows of superposed columns with richly decorated capitals. The church boasts two Romanesque crypts and a 16C cloister, plus a treasury housing precious reliquaries, ivories and liturgical ornaments.