Once used as the office for the Ministry of Commerce. It is located in the area of former palaces which were built in the reign of King Rama III (1824-1851). The land was transferred to the government in King Rama VI’s reign (1910-1925). The well preserved main building has three storeys. Some details and decorations; precum, pilasters and architraves is influenced by European architecture. The building is now used for the first national discovery museum called “Museum Siam”.