Sappaya-Sapastan

Sappaya-Sapasathan is the third and current meeting place of the National Assembly of Thailand, the bicameral legislative branch of the Government of Thailand. It is located on the left bank of the Chao Phraya River in Kiakkai neighbourhood of the Dusit District. It is the world's largest parliament building with 424,000 m2 of floor space.

Source: Wikipedia