At present, you can run round London's most interesting contemporary gallery extensions in an afternoon. But come the next century, it looks like the trip may take you more than a week.
HERE AND NOW
CLORE GALLERY, Tate Gallery, Millbank (James Stirling, 1985)
Toytown doorways and windows, gaudy railings, beigey pastelly walls: utterly Eighties, but an exceptionally solid Ur-Eighties, a building which makes you think through why you hate postmodernism, and then think again.
SAINSBURY WING, National Gallery (Robert Venturi, 1991)
In a 1966 manifesto, the American Venturi suggested that brave new architectural futures could be found by ironically reinterpreting the past. A quarter- century later, Prince Charles seemed satisfied with the vaguely Corinthian carbuncle he grafted onto Trafalgar Square. But really, it just looks like a new building posing as an old one.
SACKLER GALLERIES, Royal Academy (Norman Foster, 1991)
High Tech is too imprecise a term for this breathtaking glass-and-steel structure, which appears delicately to balance on the edge of an excavated 19th-century wall. You whiz up in a trendy lift to be suffused in soft- white light: like heaven, with Michaelangelo's Holy Family at the top.
DESIGNS ON THE FUTURE
TATE BANKSIDE: Trendy Swiss firm Herzog and De Meuron moves into Giles Gilbert Scott's old downriver power station in Southwark.
Money: pounds 106m, with pounds 50m in place from the Millennium Fund, pounds 12m from English Partnerships and pounds 1m from Southwark Council.
Deadline: Building has just started; aims to be finished by 2000.
ICA: Will Alsop is suggesting a curious bulbous object, to rest on in situ piers at Blackfriars.
Money: Around pounds 30m is mooted. Lottery bid will go in next year.
Deadline: "2001 would be poetic, and yes, I suppose it does look a bit like the bone from the film."
V&A BOILERHOUSE: Daniel Libeskind's deconstructivist heap of boxes has been upsetting a lot of people since May. The architect is currently working on the "thunderbolt" Jewish Museum in Berlin.
Money: Roughly pounds 42m.
Deadline: Around 2001, but planning permission may be a problem with an HRH-unfriendly design like this.
WALLACE COLLECTION: The inner courtyard is a haven of ornamental-garden oddness. Rick Mather Architects propose floating a glass floor over the top of it and sticking a cafe underneath.
Money: A quarter of the pounds 10m budget was pledged 10 days ago by an anonymous donor. A Lottery bid is in for the rest.
Deadline: 2000, to mark the Wallace Collection's centenary.
DULWICH PICTURE GALLERY: London's oldest public gallery, designed by John Soane in 1814. Rick Mather Architects propose a cafe and education block, plus a bronze-and-glass cloister-cum-pergola on the side.
Money: Probably around pounds 8m.
Deadline: Expected to start building in 1999.
SERPENTINE: John Miller's blueprint "walks within the footprint" of the 1930s building, sinking workshops into a new basement.
Money: pounds 3m from Lottery, pounds 1m raised elsewhere.
Deadline: Work should finish next year.
NATIONAL PORTRAIT GALLERY: Jeremy Dixon and Edward Jones, of Royal Opera House fame, fill a dingy courtyard and add a rooftop cafe.
Money: pounds 14m to be funded by Lottery bid and 1896-1996 centenary appeal.
Deadline: Building starts in 1997, aimed for completion in January 2000. JT