The house that tax built

Walk down almost any street in Hanoi's Old Quarter and you will notice something odd about the buildings. Many are barely four metres wide yet run back thirty, forty, sometimes sixty metres from the pavement, like drawers pulled out of a cabinet. Visitors tend to assume that this is simply what Vietnamese houses look like, an expression of some timeless national taste. The truth is at once more mundane and more interesting. The tube house, or nhà ống, is to a large extent the product of tax policy, land prices and a commercial culture in which the strip of street in front of your door was worth more than everything behind it.

The usual story runs as follows. Under the Nguyễn dynasty and, later, the French, shopkeepers were taxed according to the width of their frontage rather than the size of their property. Faced with such a rule, any sensible merchant would squeeze as much space as possible out of as little street as possible. Historians have since pointed out that the evidence for a frontage tax is patchier than guidebooks suggest; the shape may owe at least as much to the fact that every family on a trading street wanted its share of the passing trade. Either way, the outcome was the same: a front room that served as a shop, a narrow courtyard for light and air, and living quarters stacked further and further back.

What began as a commercial compromise has proved remarkably durable. When private building took off again after Đổi Mới in the late 1980s, families who had finally been allowed to build did not abandon the old form; if anything, they exaggerated it. Plots were divided between siblings, and then divided again, so that a house might end up three metres wide and five storeys tall, its side walls left bare in the expectation that a neighbour would soon build right up against them. Seen from a rooftop, whole neighbourhoods look like rows of books packed tightly on a shelf, some taller than others, none of them designed with the street as a whole in mind.

It would be easy to dismiss all this as chaos, and many planners have done exactly that. Tube houses are dark in the middle, hot under their tin roofs and notoriously hard to escape from in a fire. Yet the form has virtues that more orderly cities might envy. Because the ground floor is so often a shop, a café or a workshop, the street stays busy from dawn until late at night, and a busy street is, by and large, a safe one. Several generations can live under one roof while keeping a degree of privacy, the grandparents downstairs and the young couple on the fourth floor. In other words, the tube house quietly does what urban theorists in the West spent decades recommending: it mixes homes and businesses, keeps density high and puts eyes on the street.

None of this is to romanticise it. The same narrowness that keeps a street lively also makes it almost impossible to widen roads, install proper drainage or plant trees, and the steady disappearance of courtyards, as owners build over them to gain another room, has made many homes stuffier than their nineteenth-century originals. Moreover, rising land prices are now pushing families out of the centre altogether, and the buildings they leave behind are increasingly turned into hotels whose owners have little interest in the life of the street outside.

The tube house, then, is neither a relic to be preserved in amber nor an eyesore to be bulldozed. It is a reminder that cities are shaped less by grand plans than by countless small decisions, each perfectly rational for the family making it. Whether Hanoi's planners can learn from that logic, instead of simply fighting it, may well decide what kind of city the next generation inherits.