Wat Doi Suthep (Wat means temple in Thai) is located North of Thailand, in the city of Chiang Mai, on the mountain carrying the same name (Doi Suthep).
It is the most famous temple of Northern Thailand and a highly respected place among buddhists. It also is home of an Emerald Buddha statue (actually made of jade).
I had the occasion to visit it with a thai person who also showed us how to pray and pay respect to Buddha through various rituals.
From the top of the mountain, there is also a gorgeous view of Chiang Mai city when the weather is clear (which it is most of the time actually hehe).