The unprepared visitor to Peckham, wandering through this bustling corner of South London, may be taken aback to discover it has been invaded by what appears to be a large green boggle-eyed cartoon monster on seven insect-like legs. However, the alien visitor is friendly and we can be assured that no harm will come to us as there is, on its brow and clearly visible over the rooftops of the surrounding neighbourhood, an unambiguous statement of obliging intent: in large block capital letters several feet high is the word 'library'.

Outside

Peckham Library, designed by architects Alsop and Störmer and built between 1998 and 2000, certainly is an unusual beast and happily so. The main structure is a large upper-case 'L' shape, tipped over forwards and propped up on playfully-angled stilts. These give the impression that the building is somehow 'walking' and create a real sense of movement. The front and sides are clad with pre-patinaed copper panels, giving the library its distinctive pastel green hue and smooth matt texture. Variously shaped windows are arranged in a seemingly haphazard manner, while a large orange tongue lolls almost lasciviously over the roof of the building.

The north side - the back of the building - is a contrasting revelation: a delightfully colourful take on the familiar, if generally unpopular, elevations of those post-war glass and steel blocks which seem to be everywhere around London. Yet in this case, the combined effects of colour, transparency and reflection are dramatic and this surely is as satisfying as a flat, rectangular wall can possibly be.

Inside

Entering through one of two openings in the cage-like and, indeed, somewhat startling steel mesh which lines the front of the building at ground level, and ascending up through the floors, we become aware that this is not a large building. Yet despite the relatively modest scale, the library manages to pack in a learning centre, a meeting room, a local council 'one-stop shop' and a number of computers with Internet access for public use, alongside the main library and childrens' collections. The main library floor is punctuated by three large wooden pods suspended in the air and providing further space, in one case for a Caribbean collection, and these reaffirm to us that this is no ordinary library.

Yet for all the colour, stilts, pods and jaunty angulations to be found here, it would be a mistake to believe that these are merely bits of idle ornamentation, or worse still, Postmodern witticism: both inside and out there is clear method to the madness. The external form with its cantilevered upper storeys maximises the available public space by minimising the extent to which it invades the square directly in front of it. Underneath the overhang we find shelter in bad weather and shade on rarer, sunnier days. Furthermore, this leaves this corner of the square and the pedestrian route onto the adjacent Peckham Hill Street as open as possible and thus avoids the creation of dark, hidden public spaces which could potentially become blackspots for street crime.

Through being raised up on 'legs', the upper floors afford the public some wonderful views of London. In this manner, by bringing to our attention the close proximity of the centre of the capital, the library reminds us that in Peckham they are proudly part of the wider city and by no means some far-flung and neglected enclave.

Green

The building is green in more ways than one: the energy conservation strategy is commendable. The glass wall enables natural light to flood into the building, reducing the need for artificial lighting. The building is naturally ventilated, allowing air-conditioning to be forsaken. Here, the windows, unlike those of far too many contemporary buildings, actually open. That 'tongue' exists to provide shade for ventilation shafts, while a further benefit of the overhang is that in creating shade, it reduces the heating effect of bright sunlight on the south-facing front of the building. Again and again, we see that the unconventional form is most certainly the product of careful methodology.

Most tangibly of all, however, so much about this building says 'fun'. This is as far removed as could be imagined from the traditional sterility and stuffiness which we might associate with a library. It stakes a clear and precise claim that learning is not necessarily boring - come on in and have a look.

In many ways - with its unconventional aesthetic, its approach to the city and to public space and its willingness to embrace its civic responsibilities - Peckham Library is highly representative of the work of its architect, Will Alsop. A Brit whose profile is firmly in the ascendant, Alsop is the nonconformist creative force behind North Greenwich Underground and Heron Quays DLR stations in London, and head of the firm which has recently beaten off competition from the likes of Norman Foster and Richard Rogers to win the high-profile commission to design the so-called 'Fourth Grace', which will sit alongside the Liver Building on the banks of the Mersey.

The intelligence, originality and civic-mindedness in the architecture of Peckham Library are absolutely typical Alsop characteristics. Furthermore, fundamental to Alsop's work is the conviction that architecture must necessarily be interesting and never mundane. This is rarely more relevant than if we wish to 'sell' the idea of a library in an area such as Peckham.

Peckham is one of large a number of London districts popularly considered to be down-at-heel, disadvantaged, or just plain undesirable. Yet this is a corner of London with much to be proud of: it is possessed of a colourful and vibrant community, a demographic which cuts sharply and uncompromisingly across all races and social classes, and there is a genuine desire and willingness to develop and improve the area. The library continues to play a central role in that process. The London Borough of Southwark has proved itself ultimately to be atypically forward-thinking and open-minded among London borough councils by commissioning this project, and is to be commended.

Reactions

Unquestionably, the reactions have been positive: in 2000 Peckham Library was awarded the Stirling prize, perhaps the single most prestigious award the British architectural establishment has to offer to a single building. More importantly, the library is popular. People from all over the borough - and indeed from all over London - have been tempted to visit and revisit a part of London to which they may otherwise never have been drawn. Much can be learned here from the manner in which architecture has benefited the public simply by listening to it, understanding it, and refusing to build 'just another building'.