London's other Tate fights back

With a third more space, it's now a healthy, aesthetic weekend exercise option!

Ever since May 2000 when Tate Modern opened on Bankside with such ear-splitting fanfare, the dear old Tate Gallery - Tate Britain as it is now known - has been cast in the role of dowdy sister and suffered a devastating reversal of fortune.

No longer London's premier museum of modern art, it relinquished at a stroke its glamorous international holdings of Picassos, Matisses, Rothkos and the like along with its place on the wilder shores of contemporary art and its status as stamping ground for the uber-fashionable art world. Visitor figures tumbled (from 160,000 in April 2000 to 62,000 just three months later), while those at Tate Modern hit record heights: 57 million in the first year, or close to five million a month. Brit Art stars grumbled when their work was shown at Millbank rather than Bankside.

But now the fightback has begun - and in considerable style. The Tate we knew and loved is back, only bigger and - in different ways - better than ever. The handsome £32million Centenary Development has been unveiled to the public, along with the new, largest-ever-hang of British art dating from 1500 to 2001. The transformed Tate is once again the national gallery of British art it was always intended to be (and was from 1897 to 1917), and this time on a scale that was previously unimaginable.

This is the site's most significant change since the old penitentiary was torn down and replaced with an art gallery in 1897, to house sugar tycoon Sir Henry Tate's collection of contemporary British art. Its elegance and seriousness of purpose will enhance Tate Britain's standing as one of London's top museums, and the transformation has been achieved with a minimum of fuss and disruption. Moreover the new chronological hang, in place of the lambasted thematic one, aims to tell the story of British art - with sculpture as well as painting and including photography and even caricature - as you've never seen it before.

Though on a large scale, the architectural additions don't stick out like sore thumbs, inside or out. The nine large new galleries - six for temporary exhibitions (the Linbury Galleries) and four for the permanent collection - are all tucked into what was a courtyard, on two floors. They eschew the industrial chic of Bankside for a contemporary pared-down version of the old galleries they run into (only environmentally-controlled and with improved lighting systems). The 1,600 extra square metres would create a whole new museum anywhere else, and even here it increases Tate Britain's gallery space by a massive 35 per cent.

The Linbury Galleries are linked to the new permanent ones above by a wide staircase and soaring atrium that is airy and light, but the galleries themselves are painted in richer hues - reds, oranges and greens; purples and crimsons for the Linbury's first exhibition, Exposed: The Victorian Nude - which enhance the pictures that hang there, while any sense of oppression is deflected by cheerful shiny, pale American oak floors. (The paint, incidentally is by the National Trust's Farrow & Ball, and not B&Q, whatever those ads may make you think).

In addition, there's a new entrance on Atterbury Street - look out for the Second World War shrapnel wounds on the wall around it. This is usually considered an unwise thing to do to a much-loved building, but in this case it is strategically placed on the route taken by the majority of visitors who arrive by Tube (some 65 per cent in total).

There's also a brand-new shop, five refurbished galleries, improved disabled facilities, and landscaping which links the old Tate building with the new Clore extension, while making a more attractive walkway from one end of the facade to the other.

The architects behind the extension are John Miller and Su Rogers, who recently gave a facelift to the Serpentine Galleries and who first worked with Sir Nicholas Serota, overall Director of Tate, in 1985 when they converted and extended the Whitechapel Gallery (a remodelling much admired ever since).

Miller and Rogers actually first contemplated a masterplan for the Tate Britain site as long ago as 1987, though building work on the new scheme didn't start till 1998; it's taken almost four years from start to finish - six months longer than scheduled thanks to extensive flooding caused by a burst water main last year. (Look out too for the new seating Miller has designed, in Seventies-style brown leather.)