from Wikipedia Vientiane:
Vientiane (pronounced /vjɛnˈtjɑːn/, Lao ວຽງຈັນ Viang-chan) is the capital city of Laos, situated in the Mekong Valley. It is also Laos's largest city. The estimated population of the city is 200,000 (2005) while the number of people living in the Vientiane metropolitan area (the entire Vientiane Prefecture and parts of Vientiane Province) is believed to be over 730,000. Vientiane is located at 17°58' North, 102°36' East (17.9667, 102.6).
The name of the city is derived from Pali, the liturgical language of Theravada Buddhism. Its original meaning is "royal sandalwood grove" or "city of sandalwood", this tree being highly valued in classical India for its fragrance. In modern Lao, the meaning of Vientiane is ambiguous, and is often mistakenly believed to mean "city of the moon", because the words for 'moon' and 'sandalwood' are written and pronounced identically. However, the name in Thai, เวียงจันทน์, retains the etymologically correct spelling, and clearly indicates "city of sandalwood" as the meaning. The romanized spelling "Vientiane" is of French origin, and reflects the difficulty the French had in pronouncing the hard "ch" sound in the Lao word; a common English-based spelling is "Viangchan", or occasionally "Wiangchan".