Due to the lack of space, the industrial art and crafts section could not be installed in the main building. For this reason, several old houses located opposite the museum in the Rue Wiltheim were acquired and fitted out. These aristocratic and bourgeois houses had a long history as residential buildings before being re-used by the museum. Their architecture reflects the evolution of urban housing from the Middle Ages to the nineteenth century. Originally built to be used by privileged residents, they were subsequently occupied by people from all walks of life.
From the early 1970s onwards, the wing's Luxembourg life section has presented ways of living and applied arts until the nineteenth century, incorporating information about popular beliefs, farm work and old trades as well as the effects of industrialisation. The exhibition about living space also includes the exceptionally well-preserved interior architecture of the old houses.
The three houses had actually never benefited from a thorough renovation and were excluded from the 2002 restructuring plan.
In order to upgrade the important architectural heritage of these homes and to better integrate them into the operation of the museum, they benefited from a complete renovation jointly managed by the Fonds de rénovation de la Vieille Ville and the MNHA from 2012-2014. The renovation works took great care to minimize any impact on the old buildings.
The new Wiltheim wing offers approximately 1500m² of additional exhibition space and two new studios for the museum's educational service.
The fully-glazed footbridge, which now connects the main building to the Wiltheim wing on two levels, allows for a significant improvement in circulation and visitor flow.