We took a trip up to the Cu Chi tunnels, north of Saigon. Built over the course of the 1940s, 1950s and 1960s, what started as small shelters under villagers’ huts was gradually developed by the Viet Cong into a remarkable multi-storey, twisting 250 km web that went right into the suburbs of Saigon itself. The system was so complex that, during the war, the Americans found whole hospital facilities, complete with operating rooms for surgery, tanks and artillery pieces, and even theatres, all deep underground.

The guerrillas who fought down there did so for years and years, living off the odd handful of rice when they were lucky enough to get a break from tunnelling or fighting. The French, South Vietnamese and American forces all struggled to comprehend the scale of the tunnels, let alone how to respond. Eventually, the “tunnel rats” emerged, a very different breed of soldier that actually relished heading down into the dark and dangerous holes underground.

Pretty strong material to work with. So it was that much more disappointing when the site itself turned out to be a bizarre theme park of death, with astroturfed spiky pits of death, dodgy animatronic manikins “making” boobytraps, and a grainy propaganda video from the 1970s extolling the virtues of the “American Killer Heroes”. Our shuffling, hunched, stumble through the small patch of tunnels still remaining was pretty impressive, especially as these have been enlarged so that tourists don’t get wedged down there, but 30 metres of shuffle a meaningful historical site doesn’t make.

A much better introduction can be found in The Tunnels of Cu Chi, written in the 1980s by a BBC journalist and based on extensive interviews with both guerrillas and tunnel rats. Cu Chi’s a place that’s definitely more interesting on paper than in reality, which is rather sad.