Perched on a cliff top overlooking the Bay of Weligama, a beautiful spot in southern Sri Lanka, between ocean and tropical forest, Picture Window House is fully in keeping with its setting. As well as providing sweeping views over the unspoilt surrounds, the house embraces its exposure to the elements, the changing monsoon winds and local climate. These natural elements were the starting point for Shigeru Ban’s programme of an open, multifaceted residence. And were corroborated by relatively unsophisticated materials and technology that included hiring local craftsmen to finish the reinforced concrete surfaces in traditional fashion and make the plaited leaf matting. The house comprises a series of individual blocks fitted one onto the other around a complex central space that serves as living, dining and relaxation area. The open centre flows outwards onto a terrace and swimming pool placed across the front with a full view of the ocean beyond. At the rear of the house facing inland and the tropical jungle, a large timber frame wall acts as a moucharabieh, or open-work screen: a sequence of operable Persian blinds, each made up of a series of open and closed slated wooden squares, ensures air circulation and filters the outlook onto the exterior. Internally, the large central nucleus expands and narrows to create a series of interlocking spaces partitioned by handsome smoothed fair-face concrete surfaces. These create circulation routes that start from the entrance area - itself the roof of the basement - and lead to the intermediate level and the terrace overlooking the ocean. Adjacent to the swimming pool area, two ramps of concrete stairs, set lengthwise to the pool, lead to a dining and entertaining area under an undulated ceiling. The west and east flanks of the central space are in light-coloured concrete. The vast, 22-m span roof comprises a layer of locally crafted plaited coconut leaves, traditionally used in the area also as fencing - and slabs of lightweight concrete to ensure waterproofing. The soffits are lined with a weave of thin teak strips. A multitude of tiny LED lights placed in the natural openings of the weave give the impression at night of being under a starlit sky. The night zones are placed on the sides, as if hooked onto the concrete walls: on one side, the guest apartments, reached from the terrace via a path starting from a break in the wall and crossing the house; on the other, the master bedroom, a timber-clad elongated rectangular volume projecting obliquely. Full-height operable glazing leads onto an open loggia while a closely spaced row of tall timber uprights on a sidewall filters the rays of the setting sun. Water is the dominant theme on the front terrace - in the swimming pool and streaming down the wall from an overflow outlet, refreshing the air and making the ceramic tiles in the pool glisten. The airy volumes of the central area give a sense of a large covered open space traversed by circulation routes that flow up and down the different levels on the interior and exterior. Transparency is modulated, however, by slatted timber partitions, their moucharabieh tracery pattern repeated on the enclosure wall of the external patio and on the concrete walls lining the paths to the house.