Vietnam’s coastline runs almost 3,500km from north to south, and for much of its history it’s been split into distinct entities. One of the achievements of the Nguyen Dynasty, which came to power in 1802, was that it managed to unite Vietnam in a single state. Their moment was only brief; France began its conquest of Vietnam in 1859, and by 1882 the Nguyens were reduced to ceremonial status in the new French colony. Their seat of power was Hue (rhymes with sway), a river port about midway down the coast, and they left some impressive monuments in their capital.

At least one of those monuments is impressive in inverse proportions to the emperor who built it. Khai Dinh held the throne for nine years, from 1916-25; he’s remembered mainly for his compliance (and identification) with his French masters. In photos he has the self-conscious air of someone striking poses: the forms of authority have become empty ceremony. It was the practice of the Nguyen emperors to build a grand tomb outside of Hue; those of the earlier rulers Minh Mang (who ruled 1820-41) and Tu Duc (1847-1883) have a gracious, contemplative air, set amongst parkland, pavilions and ornamental lakes. Despite his lack of any real power, Khai Dinh set out to build a tomb much grander and more imposing than those of his predecessors. (A special tax was levied on the peasantry to fund it.) The earlier tombs are set in gently undulating country beside the Perfume River, with designs that draw you inward through a series of temples and courtyards. Khai Dinh’s tomb is set at the top of a steep hill, up several long flights of stairs: it looms over the landscape. The temple that houses his remains is reminiscent of Versailles, with its glass doors and non-stop ornamentation. It’s fabulous – the walls are decorated with intricate mosaics depicting an Arcadia of grottos and bamboo and storks – but (again like Versailles) the opulence is exhausting and finally offensive. In an anteroom the emperor’s gilded French dinnerware is displayed in glass cases: it’s a fascinating case study in how someone can so identify with his masters that he ends up adopting their aesthetics and manners. It made me think too about the way a thing can be valued simply because it’s old. What value does this over-the-top monument to an underwhelming man really have – except as a cautionary reminder of imperial excess? Is that reason enough to preserve it?

The palace where the Nguyen emperors lived and worked is in the centre of Hue. A moat and walls 20 metres thick surround the Imperial City; the complex is fronted by a great square citadel. It hulks low against the horizon, relying on mass rather than height for its impact. It’s a very blunt statement of power. Much of the palace was destroyed during the war with the Americans (the 17th parallel was just north of Hue); walking around it now, it requires a leap of imagination to picture it in its prime. Sometimes all that’s left of a building is its foundation; grass carpets what used to be the empress’ quarters. Parts of the Imperial City are being restored, but the wreckage has its own eloquence: it testifies to the violence Vietnam has endured in the years since the last emperor’s abdication in 1945. It dramatises the gap between then – with its ranks of mandarins and palanquins and strict protocol – and now, power asserted and surrendered. But it’s precisely time’s indifference to these relics – the neglect they’ve fallen into – that makes them so expressive. How then should we treat old things? Should we coddle them when their historical moment is past, or let time’s depredations take their course?

I found myself thinking again about the value of old things in Hoi An, a little town 140km south of Hue. Hoi An was an important sea port until the 19th century, when its position was usurped by nearby Danang. For hundreds of years it was a place where merchants from China, Japan and even further abroad congregated, and the town has meticulously preserved the buildings they left behind. It looks gorgeous in photographs – coloured lanterns slung across the street at night, candles floating in paper boats down the river. It was gorgeous in life too, but I found myself rebelling against its beauty. One of the things I valued about Hanoi was its utter indifference to our presence: we were absorbed into its flow, free to observe it going about its business. Even the Old Quarter, where most of the hotels are concentrated, was densely populated with locals. The Ancient Town in Hoi An was the sort of stage-lit, coercive experience I dislike when travelling: it felt like an entry in the World Showcase at Disney’s Epcot Centre. (“Welcome to ‘Vietnam’!”) Everything is held up for you to admire (and buy): there’s only one way to experience it. The streets were swept clean (a true anomaly in Vietnam); the locals have ceded the old centre to restaurants and tailors. There’s no lived centre to the place: it exists to sell things to tourists. It’s much like The Rocks in Sydney, which trades on its age while filling its venerable sandstone buildings with shops selling clip-on koalas. Part of me wanted the whole place bulldozed and replaced with something with a little more grit and vitality. Luckily, we were staying a short distance out of town, where there was more of an everyday rhythm.

The highlight of our time in Hoi An was a cooking class we did with Trinh Diem Vy, who owns four restaurants around town. Sitting down to lunch at Morning Glory, I was struck by the menus, which described the cultural significance of each dish and combined ingredients with palpable care and forethought. (One of Ms. Vy’s restaurants serves as her “thinking kitchen”.) I read it cover to cover. We enrolled in a class on the strength of it (and the meal that followed): Ms. Vy was every bit as impressive in person. She conceives of herself as an ambassador for Vietnamese food; in Australia she would be a TV chef, but Ms. Vy seems to prefer to work in her town, as part of her community. She taught us about some of the regional differences in Vietnam (people in the south of the country prefer their food sweet); about the lingering effects of the ration system (each family received a monthly ration of rice and sweet potato, and grew what they could on the side; meat is reserved for special occasions); about the health benefits of various ingredients. She told us too about a trip she made to Melbourne when she was first going into business to get to know the tourist market. She learned that “Australians spend a lot of money on coffee and cake”: acting on this insight, she opened a restaurant concentrating on these things. I thought of her later when we visited a museum devoted to ceramics: historians use plates and bowls to map the interaction of cultures hundreds of years ago. Vietnamese ceramics ended up as far abroad as Cairo. In their glass cases these bowls were not much to look at, but they testified to a different sort of history to the pomp of the Nguyens: the movement of goods around the globe, the meeting of different groups of people in the marketplace. Ms. Vy is carrying on the same work in Hoi An today. The culture she represents is not bound up in old things; it’s a living tradition that she helps transmit.