The rehabilitation and extension of the Chamber of Commerce of Luxembourg was an opportunity to annex the existing 5000 m2 to a project totalling 30 000 m2 of offices, a conference centre and four underground levels of parking. It is broken down into six five-level buildings connected by glazed galleries and patios. The structure of these buildings is a mixture of steel and concrete for the floors and the central cores with a metal frame and glass and steel façades. The floor thickness is reduced to 35 cm by using trussed joists with visible ties along with the stainless floor elements designed specifically for this building. There is no central support for the 12-metre span corresponding to the width of these buildings. Fire safety protection utilises modern engineering concepts: a sprinkler and other appropriate systems that have made it possible to leave the frame visible.