Wiang Kum Kam

Wiang Kum Kam is an historic settlement and archaeological site along the Ping River, which was built by King Mangrai the Great as his capital before he moved it to Chiang Mai. It was flooded and abandoned more than 700 years ago; that move became more understandable in 2005, when the ancient city was flooded three separate times as the river overflowed its banks in that area of Chiang Mai.

Source: Wikipedia