In 1996 the Swiss Confederation commissioned the architects Annette Gigon and Mike Guyer of Zurich to overhaul the ʻAm Römerholz̕ residence and the gallery, both of which had been modified several times. Their brief was to bring the out-of-date lighting and other technical facilities into line with current conservation standards in a way that would facilitate an aesthetically satisfying presentation of the collection. The remodelling was also to cater to the other needs of a modern museum.
In the late 1960s, after Oskar Reinhart's death, the original buildings, especially the residential section, had been subjected to far-reaching changes as a result of conversion into a public museum. Gigon and Guyer restored features eliminated during this remodelling so as to return the building as far as possible to its original state as a private residence. In addition, they created three new spaces in the section linking the building's two main components, the villa and the gallery. The modern architectural vocabulary they employed in this section - effectively a third, distinctive component of the whole - took its cue from the original architecture, establishing a sense of harmony between old and new. This is especially apparent in the entrance elevation, where the new exterior engages aesthetically with the façade of the villa. The plain cement slabs, for example, echo the bold masses of the villa. In addition, copper, lime and other materials were mixed into the cement in order to grant it a characteristic patina over time. The new section therefore relates to the original building of 1915 in terms of both shape and colour.