Walk the streets near the fountain square and the town reads as unmistakably French — official buildings with deep verandas, ochre villas, arcaded shophouses with their plaster going soft at the corners. But the population that filled those shops was not French, and for a long time it was not mostly Lao either. In 1943, 85 percent of the people living in Thakhek were Vietnamese, the result of a deliberate colonial policy of moving Vietnamese labourers, clerks and traders into Laos to run an administration the French did not want to staff themselves. Those families built lives here, and their descendants and the town's Lao majority now share a place whose architecture still belongs to somebody else's plan. Today around 90,800 people live in the district, according to the 2015 census.

Colonial ambition left something else behind: the ruins of a railway that never ran. The French intended to link Thakhek to Tân Ấp in Vietnam, punching a system of tunnels through the mountains under the Mụ Giạ Pass to give landlocked Laos a route to the sea. Money and engineering both ran short. Work on the road tunnel, already begun, was abandoned in 1950, and the remnants of the scheme can still be found in and around town. The idea, however, refused to die. Laos revived it, and on 31 March 2026 a concession agreement was signed for Section 1 of a standard-gauge line running 147 kilometres from Thakhek to Mụ Giạ — the first stretch of a 562-kilometre railway meant to connect Vientiane to the Vietnamese port of Vũng Áng by 2030, following very nearly the route the French gave up on.

Most travellers who come here are not staying. They are collecting a motorbike. The Thakhek Loop runs close to 500 kilometres — east on Route 12, north through the karst, then the long southbound haul back down Route 13 — and it is the reason the town has more scooter rental shops than its size would justify. Three or four days is the usual pace; two is possible if you are willing to start before dawn and finish in the dark. The roads have improved enormously, but rain turns dust to grease, heavy trucks bound for Vietnam own the connector highways, and cows, water buffalo and dogs treat the tarmac as their own. Riders come back caked in thick orange dust that takes several washes to get out of everything, and generally in a very good mood about it.

The single most astonishing thing on the Loop is not a road at all. About 130 kilometres north of Thakhek, in Phu Hin Bun National Park, the Nam Hin Bun River disappears into a limestone mountain and stays underground for seven kilometres. Tham Kong Lo is navigated by motorised longboat, and the scale defeats the boatmen's headlamps: chambers reach 90 metres across and roughly 100 metres to the ceiling, so the beam simply dissolves into black. In the dry season passengers get out and wade while the crew drag the boat over shallows. The first recorded rowing crossing was made in 1920 by five volunteers working by torchlight, an act of nerve that is easier to appreciate once you are inside. Closer to town there are lesser caves for lesser commitments — Tham Nong Pafa, the Buddha Cave, reached by walkway and concrete stairs, and Aen Cave with its river mouth, its deep pool and its Escher-like tangle of staircases lit in neon strips.

Thakhek itself is small enough to cross on foot. Behind the shops on the roundabout opposite the Lao Development Bank, narrow lanes open into a produce market where the stalls sell what the surrounding country provides — including, on some days, snake, frog, squirrel and bat. Cafés line the riverfront, the Mekong runs past a stone's throw away, and Nakhon Phanom sits in plain sight on the Thai bank, now reachable by the Third Friendship Bridge ten kilometres north. The climate is emphatic. April has hit 42.8°C. August alone delivers 562 millimetres of rain on the way to an annual total of 2,279, spread over about 132 wet days. Come in the cool season, from November to February, when the mornings are clear and the dust on the Loop has not yet begun to rise.