A midtown Xanadu

Much of Foster and Partner's architecture works well as cinema - Swiss Re was an aptly phallic backdrop for Fatal Attraction II, for example, and Canary Wharf station is a dead ringer for Metropolis. So it's appropriate that he has now tackled the greatest movie of them all: Citizen Kane.

This was Orson Welles' thinly disguised biography of William Randolph Hearst, yellow-press baron, disappointed lover and creator of extravagant buildings - above all the fabled Xanadu. To house his East Coast empire, Hearst built a more modest six-storey art deco office block in midtown Manhattan in 1928. Now Foster has turned it into a soaring glass tower for Hearst's still thriving business.

Hearst’s six-storey headquarters has been scooped out to leave a vast entry hall, where raking columns support a new 42-storey tower (below)

The original building's dark warren of offices has been scooped out to leave a void drenched in daylight. This floods through the windows in the retained facades, as well as a two-storey strip of clerestory glazing. A triple escalator climbs up from the street entrance and a double-storey waterfall cascades down glass steps on either side. The hall into which visitors then step is so vast, light, airy and full of activity that it resembles a bustling town square. If Hollywood ever needs to update Kane, it will find the set has already been built.

Foster's £270m transformation also fulfils Hearst's ambition to build an office skyscraper above the art deco plinth. The powerful raking columns that stretch up through the six-storey void support 42 storeys of offices, to which the void serves as the grand entrance lobby.

The office tower reprises the triangulated steel structure that Foster used on its competition entry for the World Trade Centre site. Its facade sets up a huge zig-zag rhythm that strides across four floors at a time.

What Foster calls a "creative dialogue between old and new" comes across as an uneasy conversation, perhaps reflecting the architect's discomfort with the facade retention.

On a more positive note, the diagrid saved 20% of the steel required for a conventional structure, 85% of the steel that was used was recycled and the building should use 25% less energy than the norm. Even the waterfall recycles rainwater. So green is Foster's skyscraper that it is expected to receive the top gold rating from the US Green Building Council.