The Savill Building is a new visitor centre for the Great Park, the historic 14,000 acre (5,665ha) forest and woodland park to the south of Windsor. The brief from the client, the Crown Estate, required that timber from the park be used where possible. Glenn Howells Architects have followed this requirement to the letter: the building is roofed with an undulating gridshell of park-grown larch laths while oak from the park was used for the roof’s outer rainscreen, fl oor and also for external features. The latest technology and engineering expertise is combined with traditional craft skills to create the gridshell roof, a fl owing organic shape which mirrors the forest skyline. The three-domed double curved structure, 90 x 25 metres on plan, is the largest gridshell roof in the UK and four times larger than its predecessor, the gridshell roof at the Weald and Downland Museum, designed by Edward Cullinan Architects and completed in 2002.