The four existing and two new office towers of the Central Tax Office are bound together by a vast new plinth building. All communal functions like congress centre, sports centre, restaurant, print shop, reception and parking are situated in this new extension. The plinth building is conceived as a dug out basement level around two large patio gardens. A huge rainwater pond covers the entire roof and is used as a cooling device for the building. A series of steel clad light wells float in the pond as the only visible elements of the sunken building.

Program: 45.000 m2
Client: Dutch Government
Support: Bureau Bouwkunde
Status: design 2001, completion first phase 2006, final completion 2007