French colonial architecture, and how much of it is left

Vietnam's French colonial architecture is easy to photograph and hard to see honestly. The opera houses and the post office are on every itinerary. The fabric that tells you what the period looked like is in the side streets, subdivided, cabled over and coming down.

The landmarks and the side streets are both worth an afternoon. The set pieces take an hour, and the streets around them take longer.

Which cities kept the French buildings?

Hanoi for density, Saigon for set pieces, Da Lat for villas, Hai Phong for the one nobody visits.

What is worth seeing in Hanoi?

The French Quarter east and south of Hoan Kiem, walked rather than listed. The Opera House of 1911 is the anchor, modelled loosely on the Palais Garnier, and the square in front of it is the place to stand. St Joseph's Cathedral, finished in 1886, sits at the end of a lane of cafes and looks older than it is, because the stone was left to weather.

The Metropole opened in 1901 and still runs as a hotel, so a drink in the bar is the only interior most visitors see. Around all of it stand the villas: ochre walls, green louvred shutters, tiled roofs, and now three families, a business and a mess of cabling per building.

The cabling and the subdivision are the honest picture, and the things to do in Hanoi page puts the quarter into a day.

What about Saigon?

Denser and grander, and mostly within one walk. The Central Post Office is the set piece: a working post office with a vaulted iron hall and painted maps of old Cochinchina. Gustave Eiffel's name attaches to it by a legend the record does not support. It went up between about 1886 and 1891, and most sources credit the design to Alfred Foulhoux.

Notre-Dame Cathedral opposite has stood under restoration for years. The People's Committee building is government offices, photographed from the square, and the Opera House of 1900 closes the top of Nguyen Hue. All four sit within ten minutes of each other, which the things to do page folds into a half-day.

Why is Da Lat different?

Because it is not a port and never had a commercial quarter. The French laid Da Lat out from 1907 as a hill station and built it residential: villas in the pine, a boarding school, a governor's residence.

The smaller northern version of the same idea is Tam Dao, laid out a few years earlier above the delta. Far less of it is left standing. The railway station of 1938 is art deco, with three pitched roofs said to echo the highland houses.

So the colonial architecture there scatters through gardens rather than lining boulevards, and a good deal of it now operates as hotels. The Da Lat hub covers what else the town is for.

What replaced the colonial street?

The tube house replaced it, mostly, built on the same narrow plots and now five storeys tall. The tube house guide explains why a Vietnamese street looks the way it does when the colonial layer is stripped out of it.

What is disappearing?

The ordinary stock, and quickly. Villas and shophouses come down for towers in both cities every year. The survivors carry corrugated iron patches, four households and the cabling that gives every photograph its foreground.

Nothing about that is hidden, and it is why the side streets are the interesting part. A restored facade tells you what an architect wanted in 1910. A subdivided villa with four electricity meters on the wall tells you what the century since did to it.

How do you walk a colonial street?

Walk it on foot, early in the morning, without a checklist. The set pieces are photographed from outside in ten minutes each, and the walk between them is where the period actually survives.

Two habits help. Look up: almost every ground floor has been rebuilt as a shopfront, and the original survives above it. And look at the shutters. Green louvres, deep verandas and high ceilings are what the French borrowed from the tropics rather than imported, which is why the buildings still work in the heat.

The museums guide covers the institutions housed in some of these buildings, and the pagodas guide is the other half of what a Vietnamese city has standing.