Other notable northern towns include Lamphun, once known as Haripunchai and founded by Mons in the 7th century; Lampang, where picturesque horse-drawn carriages still ply the streets; Mae Hong Sorn, nestled in a secret valley of exceptional beauty; Chiang Rai, a popular base for treks into the hills; and Chiang Saen, at the tip of the so-called "Golden Triangle" where Thailand's borders meet those of Laos and Myanmar.