The Thermen bathhouse stands, as the oldest stone building in the Netherlands (63 AD), for the Roman past of Heerlen. The museum around it was created in the 1970s (arch. F. Peutz) where the bathhouse was covered with the then new 'spaceframe'. On top of the museum there is a curious concrete archive tower. The building is technically outdated and lacks a relevant expression. The renovated museum makes the 'Roman secret' of Heerlen accessible to a wide audience.

The intervention knows 4 aspects: Expanding, creating a logistically clear layout; bringing unity to the fragmented and meaningless outdoor space; technically improving and at the same time making the bathhouse more perceptible; providing an appropriate expression.

The structure of the bathhouse should remain intact. A new wall of Roman masonry will be built around the excavation. On the 4 columns of the archive tower a new museum section (the 'mansio') is constructed with exhibition rooms, offices and education rooms. The new building section is clad with ceramic panels, based on the local tradition of pottery. Beneath this raised volume is a spacious entrance on a green square. A ramp runs along the exhibition rooms; after the temporary and permanent exhibition you descend along this to the circulation of the bathhouse. A glass path leads right past the excavation.

The design is surprisingly logical and makes efficient use of the existing. It is green, welcoming and rooted in Heerlen's culture. The 'mansio' is functional and flexible, so that the story can be told in ever new forms. Above all, the new museum is an appealing composition of monumental and new that confidently conveys the Roman foundations of Heerlen.