Whatever happened to the likely lads?

The closure last week of the daringly designed Museum of Pop Music in Sheffield is not the first time brilliantly purposeful architecture has rapidly become redundant.

The giant blue press-lines were switched off for the last time eight years ago, but the edifice is still known as the Financial Times printing works. The building remains the finest modern architectural landmark on the stretch of the A13 that slices through London's docklands. The dual carriageway passes the smoked glass and steel façade and the adjoining cluster of oddly pristine byroads whose names murmur wistfully of perfidious Victorian doings by a stretch of the Thames that Joseph Conrad described in his Heart of Darkness as "one of the dark places of the earth".

The giant blue press-lines were switched off for the last time eight years ago, but the edifice is still known as the Financial Times printing works. The building remains the finest modern architectural landmark on the stretch of the A13 that slices through London's docklands. The dual carriageway passes the smoked glass and steel façade and the adjoining cluster of oddly pristine byroads whose names murmur wistfully of perfidious Victorian doings by a stretch of the Thames that Joseph Conrad described in his Heart of Darkness as "one of the dark places of the earth".

The two hectares around Nicholas Grimshaw's old printing works present a heart of archness, a connecting series of stylish medium-rise office blocks without style, in colours that are not quite memorable; buildings whose stiffly padded and crudely stitched-up elevations are the architectural equivalent of a suit-to-forget from Montague Burton. The names of the roads that bind the area are achingly bathetic: Clove Crescent, Saffron Avenue, Nutmeg Lane, Coriander Avenue. They are overlooked by a gunmetal grey Travelodge and a luxury warehouse apartment development, some of whose inhabitants will no doubt be sellers of futures rather than pasts.

Two stones' throws away, beneath the A13 and under a withered wreath ("Lee RIP") fixed to the central reservation railings, trunking conduits carry the bundled spaghetti of international fibre-optic comms lines. Many of them flow out of the old Financial Times building, which is the only spicy thing left on the urban menu in Poplar. The fate of this building, and many other striking architectural works, shows how the mighty are fallen - and how fallen can become mightily different.

When Nicholas Grimshaw's award-winning building was completed in 1988, the Architectural Review correspondent John Winter told it like it was. "The Financial Times print works in London's docklands is, like other buildings in the area, an isolated object," he wrote that November. "Yet by careful location and skilful use of glass technology, the architect has made it a literally dramatic monument at what would otherwise have been a dreary road junction."

The building's diaphanous skin made it "wonderfully clear and attractive. In the centre of the press hall is a gap between the two machines. Here, one can look out across from gallery to glass skin and appreciate the splendour of the place, a splendour comparable in many ways to the generator hall at Battersea power station."

The particulars of the building's exterior are still intact. The 286 two-metre square panels of Pilkington planar glass still glint across the main façades, held in place by a then-innovative arrangement of steel dinner plate-sized pads linked to vertical outriggers. East India Dock House, to call it by its current name, still cuts a remarkable dash; give or take a few minor smears of rust here and there, the building looks surprisingly new. The crisp simplicity of the overall form is as dateless as Norman Foster's Willis Faber building in Ipswich - as jet black as the shades worn by the Blues Brothers - which the printing works superseded in terms of glazing technology.

The printing works was shut down within six years - the FT outsourced its printing - and the building lay more or less inert until a 1998 joint venture involving Stockdale Properties attempted to redevelop it into what one of Stockdale's directors called "a leisure box". That didn't work out, and developers spent more than £20m last year converting the building into a so-called internet carrier hotel operated by Global Switch London.

The building's interior is certainly no longer "wonderfully clear and attractive". Apart from two foyers and a small operations suite, it is little more than three floors of corridors and rooms humming with the switchgear of the 16 internet carrier companies that have so far moved into the building. In a 20 minute behind-the-scenes look around the premises, only two people were encountered.

Security is the key issue. Apart from swipe-card door entries, the closed circuit cameras and the two-key conduit cupboard locks, there are triple back-up smoke, water and fire alarm systems; and in each of the water-bunded rooms are precisely set out ranks of blood-red argon and nitrogen tanks which release the fire-suppressing gases within seconds of an outbreak. In the event of power failure, the three huge Perkins diesel engines in the lower ground floor plant room can power up generators to deliver a rock-steady 11,000 volts into the electrical grid within 30 seconds.

Under the floors, and within the internal walls, are layers of steel trays carrying colour-coded tubes of fibre-optic cable. This eerily silent building is, quite literally, wired. But the only things moving with any vitality are photons. So Grimshaw's building is no longer of a piece; there is a hi-tech cuckoo in the nest.

Originally designed to serve an absolutely specific purpose, the building's virtues have been cherry-picked. Global Switch London took on the building because, according to the facilities manager David Bucknall, it was waterproof, attractive and serviceable - "a bit of a tribute to Grimshaw, in my opinion."

On the other hand, "To say it was easy to convert, that's bunkum. It was a hell of a job to get the floors in. But we tried to honour the quality. It's like Le Corbusier: a machine for living in, a machine for telehouses." Bucknall, a former quantity surveyor and architectural enthusiast, loves the building - "but my take on this is that the printing process was obsolete by the time it was completed".

It is a general charge that can be applied to any building, of course; but the risk of obsolescence may be greater with higher profile architecture. And even the distinctly avant garde is hardly proof against this syndrome. In 1932, the Hoover building in Perivale, London, designed by the Modernist architect Thomas Wallis, was just such an object. This grade II listed building was finally saved by Tesco in 1992, when the down-at-heel structure had started a potentially fatal decline rooted in the depredations of weather and the after-effects of wartime bomb damage.

Its concrete walls had become highly acidic, jeopardising the reinforcing steel rods. Tesco spent millions restoring the building and its Art Deco features: the acidity was neutralised, blue and orange faience tiles were commissioned from the company that had supplied the originals, the rose garden was revitalised, the façades painted in the original colour.

The apparent demise of Branson Coates' extraordinary National Pop Museum in Sheffield - four huge, steel-clad carboys with oast-like flues on their crowns - is an even more notable example. In many ways the sculptural structures are beyond categorisation, their form is in a sense unidentifiable, and therefore dateless; safe, in theory, from any change of use in the foreseeable future.

That this has rapidly not proved to be the case is less to do with design than with the developer's choice of location and a failure to address consumer appetites. Branson Coates supplied a landmark buildings which should probably have been in London, coupled with a full-blown retail therapy aspect to the development. Great buildings, in this case, needed great T-shirts.

Grimshaw's creation on the A13 may offer an interesting kind of hope. Nomura's bargain-buy Dome is directly across the river from the old print works. Both structures are, in a sense, duds - but with one vital difference. Grimshaw's building met its original brief to the letter, and, regardless of its current contents, it will remain of genuine architectural interest. The Sheffield quadrille may surprise us yet.