The expansion consisted of equipping the museum with sophisticated preservation laboratories and providing it with the best thermal control techniques. Large underground spaces were built to accommodate the various collections and archives. A double envelope concept is thus developed to manage the degree of humidity and to favor the admission of natural light while maintaining the durability of the original envelope.
The site being located in a densely developed area of the city centre and bordered by high adjacent buildings, the challenge was to integrate the expansion into this context, giving it importance. The combination of proportions and volumetry, as well as the limestone lining, allow the fusion and continuity of the two buildings, the existing one and the extension, while integrating the modern part in the historical and constructive tradition of the Golden Square Mile. The newly created lateral glass entrance opens like a cathedral nave where a totem of 33 feet in height acts as a pillar structuring space.