The municipal architect of Aachen, Laurenz Mefferdatis, built the Catholic parish and deanery churches from 1721-1729 in the renaissance style. The bottom part of the south tower originated from a previous church of the 12th century and is thus one of Eupen's oldest extant buildings. The interior furnishings are in the style of the Aachen and Liège baroque. The hall church with its three naves is impressive on account of its roominess and precious furnishings.
High altar
The baroque high altar was donated by the citizens of Eupen, mainly the cloth merchants, and was made in the years 1740-1744 to plans by the Aachen architect Johann Joseph Couven.
The elaborate programme of images includes carved mid-reliefs, six pillars with depictions of the twelve apostles, St. Nicholas and St. Lambert, above them Christ with the cross and God the Father, at their feet the globe and, as the crowning glory, the Holy Ghost in the shape of a dove in an aureola
Communion rail and altar
Since the conversion work done in 1980, the communion rail dating from 1740 has been divided at the level of the centre aisle and segregates the body of the church from the chancel. It is one of the most valuable decorative items in the church, consisting of a black marble frame, fitted with twelve brass reliefs and 48 short brass columns.
Six of these so-called balusters were used in the conversion for the base of the new altar. They support a slab of dark marble that weighs some 750 kg.
Side altars
The two side altars also date from the baroque period and correspond to the high altar in terms of their style and construction. The statues, which were not made until the 19th century, depict the Annunciation and the Madonna with her mother, St. Anne.
Pulpit
The pulpit, erected in about 1730, is one of the oldest works of art in the church. It is adorned with depictions of Christ the Redeemer, the Mother of God and St. Joseph.
The rear wall, with a bas-relief of St. Nicholas, forms a transition to the so-called abat-voix, which is crowned by a figure of God the Father on the globe, pronouncing a blessing. The underside of the abat-voix is adorned by the dove of the Holy Ghost in an aureola. The balustrade of the pulpit stairway appeals with its open carvings.
Pews
A total of 84 pews were made of oakwood in a uniform style between 1730 and 1850. Some were commissioned and financed by the authorities of the town, others by influential citizens. If required, one could rent a pew in the long term. Tenants and donors would have their name carved in the wood, and that gives us an idea today of who the notabilities of the town were at the time.
Pillars
Fourteen pillars carry the massive, dome-shaped groin vault.
Confessionals
The confessionals, decorated with magnificent rococo carvings, were made in 1771. They were the work of master cabinet-makers from Eupen. The coat of arms of the donors can be seen in the gables of the two front ones.
Organ
The first large organ was made between 1760 and 1763. In the decades that followed, it was refurbished, restored and technically extended, most recently in 1966. Today, in fact, the organ at St. Nicholas' Church hardly has anything more in common with the original one at all.
