Interpretation centre, Limpopo, South Africa by Peter Rich Architects.

Located at the confluence of the Limpopo and Shashe rivers, is Mapungubwe Hill, a World Heritage site. Etched on stones uncovered from there, are ancient motifs that have provided the inspiration for the plan of this extraordinary building. It tells the story of the site in a series of gloriously, vaulted, exhibition and learning spaces. The building consists of ten free-form vaults, the tallest of which is 14.5 metres high, and a number of regular barrel vaults and domes. All are arranged on a roughly triangular plan connected by ramped walkways. The method of vaulting relies on clay tiles set on edge and bonded with quick - setting gypsum mortar. Similar methods are used in traditional vaulting in the Catalan region of Spain amongst other places. It enables the craftsman builders to readily interpret fluid forms. It is interesting too that the building finds some kind of spiritual, even aesthetic precedent in the work of Antonio Gaudi, who of course was of Catalan origin, and who was able to express local myth and culture in the architecture he created. The Interpretation Centre, a triumph for Peter Rich Architects, is shortlisted for this year's Aga Kahn Award for Architecture.