Chiang Saen is a town in northern Thailand on the bank of the Mekong River that is known for its historic ruins. Though Chiang Saen is a small, sleepy town by modern standards, until the 14th century it was home to a powerful independent kingdom. Ruins of the ancient kingdom of Chiang Saen can still be seen, including temples, Buddha images, and the old city walls, and there is an excellent history museum.
Chiang Saen is also near the "Golden Triangle" where Thailand, Laos, and Myanmar meet. The town offers hotels and guesthouses as well as restaurants, banks, and an immigration office.
Chiang Saen is located about 60 kilometers north of Chiang Rai. It is set on the bank of the Mekong River opposite the town of Ton Pheung, Laos. Do note that the Thailand-Laos ferry crossing in Chiang Saen is not open to foreigners - go to nearby Chiang Khong instead.
Public buses run regularly between Chiang Saen and Chiang Rai and the trip takes about 2 hours.