Architecture: Destroying what the B-52s could not: Hanoi's loveliest buildings survived war. Now they face an even greater enemy: developers. Raymond Whitaker reports

Silk has been sold for close to 1,000 years along Hang Dao street, in the heart of old Hanoi, although the clothes cramming the tiny shop at No 59 are made of humbler fabrics today.

Next to the shop is a dark passage, so narrow that a Westerner has to edge down it sideways. Leading off this tunnel is a series of rooms, one behind the other, each occupied by a family. The only daylight comes from each end of the passage. More than 100 people live here.

No 59 is a 'tube house', a form of architecture unique to the ancient quarter of Vietnam's capital. Soon after Hanoi was founded in 1010, traders and craftsmen occupied the area known as the 36 Streets, each named for one of the original guilds - silver, silk, paper, fish-grillers and hat-makers. Space was so scarce that the only way to expand was backwards: some houses, while only 6ft wide, are up to 300ft deep.

As heedless modernisation has removed the heart of other Asian cities, the 36 Streets quarter, with its low tiled roofs, crumbling temple gateways and winding alleys, is a precious reminder of what they have lost.

Hanoi's colonial legacy is equally distinctive. The French, who colonised Vietnam in the mid- 19th century, laid out long boulevards lined with grand villas and even a scaled-down replica of the Paris Opera. It is probably the finest collection of French colonial architecture anywhere, a semblance of Aix-en-Provence gone to seed.

Hanoi's character has survived despite American bombing largely because economic collapse prevented the implementation of a typically ruthless, Soviet-inspired redevelopment plan that would have razed large areas of the city. While Asia's 'tiger' economies shot ahead, bulldozing much of their heritage in the process, Hanoi sank into picturesque decay.

Vietnam is now modernising, too, and at a pace that poses a greater threat to Hanoi's distinctiveness than decades of war and Communist mismanagement. While the best buildings are restored, including the opera house, lesser examples of traditional architecture are unsympathetically renovated or swept away.

The opera house is to be overshadowed by a 20-storey hotel. Hanoi Plaza, a 20-storey residential, shopping and office development, will have 'accents from the French colonial period' to blend with its surroundings, says its Australian developer, Peter Purcell. Mr Purcell has been quoted as saying: 'To make omelettes in this city, you have to break some eggs.'

In the colonial quarter, preservation will mean heartache. Hanoi's municipality has announced plans to remove 2,000 people from 150 French colonial villas along two of the quarter's main streets, Tran Hung Dao and Ly Thuong Kiet, before restoring them to their original state for rental to foreigners.

The stakes are highest, however, and the problems most intractable, in the 36 Streets. For every developer who wants to raze large areas of the quarter, there are hundreds of inhabitants, like those at 59 Hang Dao street, who want to improve their living conditions now that doi moi (economic reform) has brought greater prosperity. In street after street, rooflines are being broken by new buildings - still only 6ft wide, but several storeys tall - many in an inappropriate rococo style that makes them resemble slices of wedding cake. Building regulations are ignored or circumvented by bribery: the profits to be made exceed any fines that might be levied.

'If this goes on, the 36 Streets will be destroyed,' lamented Ha Van Que, of the National Institute for Urban and Rural Planning, which is at the centre of official attempts to gain some control over redevelopment. Backed by foreign groups such as Unesco, which has proposed a dollars 600m conservation scheme, and the Australian- founded Friends of the Architectural Heritage of Hanoi, it has drawn up a plan that bans high-rise buildings in the city centre and lays down regulations for the 36 Streets. But the conservationists are opposed by equally powerful officials who regard the ancient quarter as an embarrassing relic of the past. While the talking goes on, the city's architectural unity is being destroyed piecemeal.

It is questionable whether any body in Vietnam is capable of the delicate social engineering required both to preserve Hanoi and satisfy the aspirations of its people. It is hard to be optimistic when the capital's fate is in the hands of a people's committee that only three years ago demolished its headquarters, one of the most stately of the French colonial buildings, and erected a concrete throwback to the Fifties of which Stalin would have been proud.

(Photographs omitted)