Mae Sai (GPS: 20.4403, 99.88217; Thai: แม่สาย ) is the border town between northern Thailand and Myanmar. It is the northernmost town in Thailand. From here, one can cross to Tachilek in Myanmar. There is really not much to see in either Mae Sai or Tachilek - which you can cross for a day trip - other than the novelty of being at the northernmost town in Thailand, and the claim for having visited Myanmar.
I was at Mae Sai when I explored the northern part of Thailand with some friends who are now AsiaExplorers members. We were actually passing through it on our way to the Golden Triangle, and stopped at Mae Sai for lunch.
Mae Sai is named after the river of the same name that separates Thailand from Myanmar. A small bridge crosses the Mae Sai river into Myanmar. If you are thinking of Tachilek, be sure to note that the border closes in the evening, do be back early or else you will be stranded on the wrong side of the river.
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