After the extension, two building complexes, physically connected by an underground gallery, face each other across Unterlinden Square. The medieval convent consisting of a church, a cloister, a fountain and a garden stand to one side. On the other side of the square, the new museum building mirrors the church’s volume and, together with the former municipal baths constitutes a second, enclosed court.

Between the two museum complexes, Unterlinden Square has recovered its historical significance, recalling the times when, across from the convent, stables and farm buildings formed an ensemble known as the “Ackerhof”.  The bus stop and parking lot existing prior to the museum's renovation have now become a new public and urban space. The Sinn canal, which flows under Colmar’s old town, has been reopened, becoming the central element of this new public space. Close to the water, a small house marks the museum's presence on the square: its positioning, volume and shape are those of the mill that once stood there. Two windows allow passers-by to look downwards at the underground gallery connecting the two ensembles of buildings.

The architects were looking for an urban configuration and architectural language that would fit into the old town and yet, upon closer inspection, appear contemporary.

Moved to the centre of Unterlinden Square, facing the canal, the entrance to the expanded Museum leads to the convent, whose facade has been delicately renovated. The renovation works were carried out in close collaboration with the architects of the French national heritage department.

Museological components from the recent past were removed and the spaces restored to an earlier state. Original wood ceilings and reopened formerly blocked windows looking out on the cloister and the city are now revealed. The church’s roof has been renovated, and a new wood floor installed in the nave. Visitors walk down a new, cast concrete spiral staircase leading to the underground gallery that connects the convent with the new building. Inside, Herzog & de Meuron designed the underground gallery and the new exhibition building (now called the “Ackerhof”), which present the 19th- and 20th-century collections, along contemporary, abstract lines. The space on the second floor of the Ackerhof is dedicated to temporary exhibitions: its gabled roof and exceptional height (11.5 meters) reflect the proportions/volumes of the Dominican church standing opposite. The central space of the former municipal baths, the swimming pool (“La Piscine”), is now connected to the new exhibition spaces. It serves as a venue for concerts, conferences, celebrations and contemporary art installations. The other spaces of the former baths house the administration of the museum, a library, a café facing the new courtyard and the Colmar Tourist Office facing Unterlinden Square.