The new Grenzing organ in the beautiful gothic Cathedral of Brussels is located laterally high up in the triforium on the north side of the nave, with the pedal in separate towers in adjacent bays. Part of the organ is hung under the organ loft and the main body of the instrument, and takes advantage of the space within the arch to allow a large instrument..

This distribution has the advantages of distributing the weight and reducing the projection into the nave to a minimum. The pedal towers, in 2 levels, similarly use the spaces of the arches. Separated almost 4 metres from the main body of the instrument, they have medieval precedents such as in Chartres and in Haarlem

This modern interpretation of medieval audacity uses steel to achieve an almost invisible structure, supported and tied back into the triforium for stability.

Within the organ this structure is built up in modules containing each element of the instrument, a system which offered advantages for transport and in erecting the organ on the cathedral floor before lifting into place.

The architectural language of the organ cases seeks to reconcile traditional craftsmanship and decoration with contemporary forms. A light finish is achieved with the combination of natural wood with polychrome and gilding to enrich it, especially in the decorative pipe shades. These carry some of the colour found in the lower part of the cathedral up to the barer area of the vaults.

The pointed angled tops to the pipe towers are counterbalanced beneath by curved brackets and in the 'cul de lampes' below each suspended element. These contain mechanisms and access below the wind chests and form decorative elements to finish the undersides of the cases.