Yet if physical change is minimal, the way the square is perceived and used by people is being radically transformed. Not for nothing is the project grandly entitled "World Squares for All". And this exercise in reclaiming the city spreads much wider than Trafalgar Square. As Foster and Partners director Spencer de Grey points out, you can now walk all the way from Leicester Square, through Trafalgar Square, across the river on the new Hungerford footbridge, past the South Bank complex to the Tate Modern and then back over the river on the Millennium footbridge to St Paul's Cathedral, crossing only one road with traffic en route.
"This is a major piece of joined-up work," says de Grey. Inserting and reinforcing pedestrian links through the city is what it's all about. The street cutting off Trafalgar Square from the National Gallery has been closed to traffic, at the lower end of the square the statue of Charles I has expanded into a pedestrian-friendly paved roundabout, fencing along road kerbs has been removed, pavements have been widened and roads narrowed to single carriageways. Semi-mature London planes have been planted to link up existing boulevards. And the forest of poles supporting street lamps, traffic lights, security cameras and road signs has been drastically thinned out.
As for the design of the new elements within the square, Foster and Partners has taken its cue from the existing design, by Charles Barry in 1840. "Barry's design is wonderfully bold and simple, and we have sought to continue this ethos," says de Grey.
The square is now more than an isolated destination for tourists, political rallyists and pigeons
Accordingly, a clutch of new facilities, including a cafe, a public toilet, a maintenance depot and two disabled lifts, have all been secreted behind the granite retaining wall beneath the upper terrace.
Wherever possible, original components and materials have been recycled, such as the massive granite balustrades to the upper terrace, which now line either side of the new flight of steps.
Now that central London's torrent of traffic has been restrained, Trafalgar Square can serve as something more than an isolated destination for tourists, political rallyists and pigeons.