With its cramped medieval Old Quarter, French colonial avenues, and scattered lakes and pagodas, this city of 4 million had long retained the feel of an overgrown village.
But Vietnam's economy has averaged over 7 per cent growth since 2001, and a wave of money has poured into property. Stately villas in the French quarter have been bulldozed to make way for 10-storey office complexes.
"The old living style in the ancient quarters is changing," said Tran Quoc Thai, vice head of the conservation division at Hanoi Architectural University. "It's inevitable."
Already high property prices shot up further in 2007 as international investors pumped an estimated 5 billion dollars into Vietnam's market. New regulations will allow foreigners to buy property on the same terms as Vietnamese, promising a further influx of buyers.
International property firm CB Richard Ellis in a report Monday predicted that continued high demand and low supply in Hanoi would send prices still higher in 2008.
A spate of new developments have broken ground or are nearing completion. In what was once farmland on the city's western edge, the 336-metre-high Keangnam Hanoi Landmark Tower, slated to be the world's 17th tallest building, is under construction.
The tower, part of a billion-dollar office and residential complex, is being built by South Korea's Keangnam Enterprises. Rival South Korean developer Posco recently announced plans to build a 3 billion dollar satellite city outside Hanoi.
A Vietnamese state-owned firm has developed the huge Ciputra development of mixed residential towers and villas north of the city.
Hanoi's governing body, has implemented policies to conserve the city's cultural heritage, with areas like the "36 Streets" from the era when it was a collection of imperially chartered craft villages, many buildings now have landmark status, and all new construction must be approved by a board of management.
In the French Quarter, city officials encourage developers to design buildings aesthetically consistent with colonial French architecture. This approach has been less successful.
"You cannot simply slap on a few arches and pillars and expect to get beautiful French colonial architecture," said Le Cuong, a Vietnamese-born French architect who has been working on architectural conservation in Hanoi since 1987.
Cuong said many of the new colonial-style high-rise buildings violate basic principles of classical French architecture, builders sometimes ignore regulations intended to prevent overdevelopment and accusations of corruption are widespread.
The influx of wealth is also changing the look and feel of street life in Hanoi, where a growing number of cars are seen alongside bicycles and motorbikes.
In January, city authorities ordered an end to all sidewalk, bicycle and shoulder-pole vendors, a traditional feature of Hanoi's streetscape. But the ban was called off amid public criticism.
While the transformation of Hanoi is partly driven by commercial concerns, it is also influenced by the desire of both citizens and government for a more modern city.
"The local government authorities often have this idea of a 'civilized street'," said architecture expert Thai. "It doesn't always make sense."
Thai said that while it was logical to push for a cleaner, more orderly Hanoi, this should be done by inspecting the foods sold at street markets and by licensing mobile vendors, rather than by banning the elements that give Hanoi its charm.
Street vendor Nguyen Thi Gai, 45, who travelled 16 kilometres by bicycle from her village to Hanoi on Monday to sell homemade hats to tourists, agrees that more regulation is not necessarily a bad thing.
"Vendors shouldn't be able to just go around selling freely," Gai said. "They should have to buy a ticket. Otherwise just anyone can sell."
Gai was selling her hats on Nha Tho Street, one of the chicest in downtown Hanoi. Most of the buildings on the street near the Cathedral of St Joseph are quaint French colonial townhouses.
A long single-storey colonial era stone building at the end of the street was torn down last year. Asia Tower, described as "a high end boutique office building", which a simulated French colonial facade has sprung up in its place.