The three-aisled, neo-Gothic hall church with a 60-metre-high tower was built from volcanic coquina clad with tuff slabs. The stepped buttresses supporting the nave and chancel of the church, as well as the enormous, slate-roofed gable roof, are particularly striking on the outside.

The bright, clear interior with a cross-ribbed vault is characterised by a consistent symmetry of the longitudinal axes. The three large picture windows of the choir with the Annunciation and the Birth of Jesus and - according to the patrocinium - the Assumption of Mary into heaven are striking. The three altars in Gothic style are by the master Caspar Weis (Frankfurt/Lahnstein). The church building was built from 1888 to 1891 after the elevation to an independent parish in 1887 at the instigation of the first parish priest of Mülheim, Heinrich Roedelstürtz. The architect of the church and rectory was Caspar Heinrich Pickel from Düsseldorf.