Ubon Ratchathani is one of the main cities of southern Isaan, close to the Lao and Cambodian borders and set around the Mun River. It is practical, spread out, and not immediately beautiful, but it has a strong Buddhist culture and enough distinctive temples to justify a day before heading to the Mekong or Laos.
The city's identity comes into focus around its temples. Wat Phra That Nong Bua gives Ubon its most striking skyline, Wat Thung Si Mueang preserves a lovely wooden scripture hall over water, and Wat Supattanaram shows the mix of Thai, Khmer, Lao, and Western forms that marks this border region.
Ubon is best known nationally for its Candle Festival, when huge carved wax floats are paraded at the start of Buddhist Lent. Outside festival time it is quieter, with markets, riverfront food, and forest-monk traditions nearby. Use it as a city base for Pha Taem National Park, Khong Chiam, and the Mekong, but do not rush through without seeing the town itself.