Gustafson Porter + Bowman:: The Treasury Courtyards between St. James Park and Whitehall occupies two roughly square cut outs that once served as light wells in the Treasury’s classic architectural form, the courtyards feature an east-west circulation route that that links to an interior central court. Within each courtyard the axis is intensified by a perpendicular movement, resulting in a cruciform framework that is then softened in plan. In the West Courtyard the subtle raising of the ground plane creates a causeway along the central axis that is arced horizontally and vertically. In plan view, water appears to slip beneath the causeway. For large events, the pools are drained and the dished slope is available for gatherings. A lighting trench traces the courtyard’s perimeter, strengthening the sense of transition between interior and exterior.

The East Courtyard scheme uses the device of shaped evergreen hedging to divide garden rooms for outdoor gathering, relaxing and reading. The hedges define intimate sub spaces within the larger courtyard, spaces that are activated by a narrow rill of moving water that runs along three of the courtyard’s four sides. Accommodating a stairwell, a cafe and an adjacent library, four quadrants are textured by plant beds and offer seating that is integrated into the hedges. Like its counterpart to the west, the courtyard as a whole must be entered, moved through, occupied and discovered a number of times before it is fully perceived.

Located over the top of the Cabinet War Rooms, the West Courtyard presented challenges in developing the ground plane to incorporate tree pits and drainage to create a mature landscape. In collaboration with the project architects, the landscape architects developed the ground slabs to enable sufficient planting depths for mature trees that were craned in to place over the top of the buildings. Water features with their necessary drainage, pump rooms and water treatment plants were fully integrated and coordinated with the ground slabs.

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Client: Bovis Lend Lease
Location: London, United Kingdom
Status: Completed 2002 and 2004
Architect: Foster + Partners
Structural Engineer: Waterman Partnership
Mechanical Engineer: Waterman Gore
Main Contractor: Bovis Lend Lease
Water Feature Specialist: OCMIS
Lighting Designer: Speirs + Major
Quantity Surveyor: Atkins Faithful and Gould