Winner of the competition launched in 2007 for the extension of Assen’s Drents Museum, Erick van Egeraat’s programme puts the accent on integrating architecture and urban context, creating a series of parks and water canals in the heart of the city. His solution to the extension brief of putting much of it underground, allows for layered functionality and effect. With this enlargement the museum, whose collections range from archaeological exhibits to modern art, has now acquired adequate space for top-drawer temporary shows. Of crystalline purity and intriguing luminosity, the new hall has dual-façade walls on either side whose upper parts - almost at ground level - are fully glazed, daylighting the whole area. The roof of the new wing is a sort of natural hillock laid out with walkways, lawns and parallel garden beds set in staggered order. The sides of this stepped roof are the glazed parts of the showroom walls beneath. The underlying theme of connection is implemented with watercourses that link the existing building, new hall and urban fabric, meshing materials, spaces and different types of light. The extension is a flowing, flexible area. Although there are no evident partition walls, spatial distribution is clearly perceptible as the underground environment follows the differences in height of the walkways on the terraced roof above. The hall is closed by a large oblique glazed span that cuts across the room. Rising from a height on a level with the ground outside, the window frames the view from below out onto the landscape, the buildings standing against the sky. Adjacent to this, a full-height glazed insert gives on to a sort of underground patio receiving shimmering light reflected off a nearby watercourse. Old and new volumes are linked by matching and contrasting elements. The wooden fencing motif on the old roof is echoed in the wood-clad frames of the extension visible from outside. The balustrades marking out the walkways on the new roof are also in wood, adding to the landscape’s natural appearance. The glazed ribbon windows ushering light into the belowground exhibition room act as a counterpoint to the glazed plinth on which the existing building, a former coach-house, now stands. The lift taking visitors from the ground floor entrance to the below ground extension is also glass sided, while the helical staircase is a further element adding light and airiness.