Not so very long ago, the idea of building any kind of skyscraper in Britain had come to seem absurd. The Americans were good at them, but when we tried it, we ended up with stumpy old Croydon, or the half-hearted towers of the City of London. Those were offices. And when it came to residential towers, well, they were a byword for disaster. Concrete council blocks? They fell down, didn't they, or at best were infested with cockroaches and inhabited by terrified old couples isolated by broken lifts and drugs dealers? By the mid 1980s, towers had become so unpopular that there was real support for a proposal to demolish every single one on the capital's skyline.

Of course, the very tall saw-tooth concrete towers of the Barbican in London somehow managed to avoid all those problems, but it was a long time before everyone clicked: towers are fine to live in, so long as someone looks after them. Once that lesson was learned, they became positively fashionable and people started to like the look of them again. Thus an abandoned and supposedly derelict 1957 council tower block in East London by Sir Denys Lasdun - Keeling House - has just been transformed into expensive private apartments: hey presto, a liability becomes an asset. This new-found modishness has come just in time for towers to meet the next challenge: how to encourage lots more people to live in cities, especially cities such as London that are under huge pressure to provide more homes?

All the other skyscrapers now being proposed are the result of a conventional client-architect relationship. Nicholas Grimshaw's and Richard Rogers' rival office towers at Paddington, Norman Foster's upended Zeppelin on the Baltic Exchange site in the City of London, Ken Yeang's shaggy eco-tower at the Elephant and Castle, sundry other proposals for London Bridge and Hammersmith and Canary Wharf, not to mention Manchester and Birmingham and Liverpool - all these are the result of developers and landowners wanting floorspace of a particular type, and inviting architects to design it for them. Marks and Barfield are different. They like to do things in reverse. Nobody rang them up and asked them to design a huge observation wheel on the banks of the Thames: it was their own idea, and they made it happen, and almost everybody is glad they did. Since they don't want to spend the rest of their lives doing more giant observation wheels, they then sat down and considered what they would ideally like to do next. The result, Skyhouse, is what you see here for the first time: a new take on the old idea of integrated urban living.