The project searches for a built synthesis between the past—the church destroyed in the war, the existing—the small chapel, and the future—the Diocesan Museum. The St. Kolumba church ruin is to be “built upon” and the “Maria in den Trümmern” Chapel from Gottfried Böhm is to be integrated within a new, larger building volume. Largely following the wall planes of the last church, the museum building will restore the volumetry of the St. Kolumba Church in a newly interpreted form. This way of thinking adopts the centuries-old tradition of changing, complementing and enlarging the church buildings “from within”, while retaining the location, the consecrated place.
While the ruin is stabilized and protected, it remains nonetheless recognizable. Analogous to the preservative nature of completing the window openings with masonry, the remains of the church façades will be built up to protect the open wall parapets threatened by erosion and the open historical excavation site.
The uppermost museum level, which almost completely covers the ruin, allows a space to be created over the site—an "interior" exterior space. It is a space whose walls and roof are full of holes—like its floor.
The museum building can thus become a protective roof and a protective envelope for the remains of the destroyed church, while housing, preserving and protecting ecclesiastical objects of art on the inside, anew. The museum becomes a connecting link between objects of art and a consecrated place—as housing for one and a "shield" for the other.
The small chapel is tied into the new volume as an autonomous building—like a stone in its setting. The museum opens up with a great court over the chapel, so that its main part, the octagon, stands under the open sky.
The museum is constructed primarily with two materials: concrete to bear the loads and black bricks to clad, enclose and protect. The primary structural elements in concrete—the space-defining pillars paired with structural wall slabs—densify in the uppermost floor into a spatial lattice of wall slabs, floors and ceilings.
The new supplementary masonry on the perimeter church walls and the skylight roof level, which is porous and unheated as well, consist of dark bricks laid offset to produce open gaps. This same brick, laid without gaps, however, forms the outer layer of the structural concrete walls, as well. The layers of masonry on the façades, with their varying degrees of porosity, allude to the closed, interior spaces lying behind them or the open outdoor spaces—reminding one with this attribute of the perforated construction of Cologne's Dome.
The museum spaces possess a skylight, a sidelight, or both, at times. The walls are made of unfinished concrete or can be painted—white, in color or with a gold tone like one of the works of art—the wall painting of Jannis Kounellis.