A machine for eating mussels and chips in

It's the hippest place in London at the moment, a vast new subterranean Belgian restaurant in Covent Garden staffed by men camping it up as Trappist monks

Belgo Centraal in Covent Garden, London, is one of those restaurants that can hardly fail. It might be steamy and crowded and more like a disco shoehorned beneath the arches of a railway viaduct, but therein lies its future success. Forget the food: it looks like a place that any self-respecting cultural tourist, student, backpacker or smart-arty will have to eat whether they can stick mussels and chips or have a palette attuned to syrupy Belgian beer or not.

In fact, the food - as the original Belgo, which opened in Chalk Farm in 1992 - proves, is tasty, reliable and extremely popular with the young of all ages, from eight to 80. The success of the burgeoning Belgo chain, owned by Dennis Blais (a French Canadian) and Andr Plisnier (Anglo-Belgian) owes as much to its Bladerunner-meets-Alien aesthetic as it does to its novelty food (novel to the English, that is), served by chaps camping it up as beer-serving monks. Sounds silly? Of course it is, but it is great fun and only the most po-faced are unable to enjoy these batty seafood kitchens.

The Chalk Farm Belgo, an instant success, was extended by Ron Arad Designs to great acclaim; the same team, led by Ron Arad and Alison Brooks, have shaped Belgo Centraal, which is probably the most extreme restaurant, at least in terms of looks, anywhere in Britain. But then, Covent Garden, so very genteel in recent years, appears to be enjoying something of a design revival. A few yards away from Belgo Centraal is the new Jones Restaurant and Bar. Reviewing it in last Saturday's Independent, Emily Green - having said the food was good - added that a "space age caveman would feel at home. 'The Flintstones meet Star Trek' and 'Dan Dare and the Troglodyte' were two descriptions of the aesthetics behind Jones's expensive and purposefully silly design - both comments made by admiring friends of the establishment."

If you changed the name Jones to Belgo, the same review might apply equally well to Arad's design. The difference is that while the scale of Jones is familiar, that of Belgo looks set to enter to the Guinness (sorry, Trappist) Book of Records as the longest, darkest and, apparently, most intimidating restaurant in the world. But, this is a first impression by someone who finds determinedly fashionable restaurants as daunting as white, minimalist art galleries.

No, Belgo Centraal might be extreme - an underground joint of immense length reached by a veteran and industrial lift powered by Prozac and lined with contemporary interpretations of refectory tables and benches. This wholly memorable design was realised on a shoestring, the sheer volume of what was once Smith's restaurant, forcing Plisnier, Blais, Arad and Brooks to spread their budget as thinly as margarine in a snack-bar sandwich. But what a spread. While there is no doubt that Belgo Centraal is more like a nightclub in full swing than what we have come to expect of a restaurant, this space is immense fun and proof that an imaginative architect can breathe unlikely life into the most unwelcoming under-the-pavement premises.

To an extent, the new Belgo draws on tricks established at Chalk Farm. The chefs are on full display and very much a part of the experience, waiters display the same odd habits, the food is pretty much identical and the decoration (the same thing as the architecture here) is so enjoyably adventurous that it would take a mean-minded soul to carp about its limitations (designing restaurants in basements is never easy) - or, perhaps, someone for whom mussels and chips is about as attractive a culinary proposition as tripe and onions.

JG