Vientiane is the capital and largest city of Laos. Comprising the five urban districts of Vientiane Prefecture, the city is located on the banks of th…Vientiane is the capital and largest city of Laos. Comprising the five urban districts of Vientiane Prefecture, the city is located on the banks of the Mekong, right at the border with Thailand. Vientiane was the administrative capital during French rule and, due to economic growth in recent times, is now the economic center of Laos. The city had a population of 840,000 as of the 2023 Census.