Or better know as the White Temple. It is located about 13km south of Chiang Rai city. Although it is a beautiful piece of art, personally I would not call it a temple. I did not see any monks, besides the fact that the main building is housing an beautiful Buddha image.
To quote the Wikipedia "It is a contemporary, unconventional, privately owned, art exhibit in the style of a Buddhist temple. It is owned by Chalermchai Kositpipat, who designed, constructed, and opened it to visitors in 1997. It is open all year round and admission is free."
The latter might not be true anymore as there has been an announcement that starting of 1 October there will be a 50 Thai baht entrance fee (with free bag) for foreigners. Well that explains the 50 THB sign that I totally ignored.