The redevelopment - conceived by recent Stirling Prize winners Wilkinson Eyre Architects - does not shy away from ambition. The Museum's central courtyard will be roofed over with glass, creating an exceptional public arena, while the Museum's gallery space will be increased by no less than 70 per cent - much of it coming into being next year, when two new galleries open. One, called London before London, will be devoted to pre-history; the other, World City 1789-1914, to the era when London was the world's pre-eminent capital, the fulcrum and reflection of an empire which had dominion over a quarter of the world's population. Simultaneously, the Museum will gain its first outpost, Mortimer Wheeler House in Hackney, which will offer greater public access to its burgeoning archaeological and social history collections which, at the moment, are too often an unknown treasure.