The country is a kingdom, a constitutional monarchy with King Bhumibol Adulyadej, the ninth king of the House of Chakri, who has reigned since 1946, making him the world's longest-serving current head of state and the longest-reigning monarch in Thai history.The king is officially titled as the Head of State, the Head of the Armed Forces, an Upholder of the Buddhist religion, and the Defender of all Faiths. The largest city in Thailand is Bangkok, the capital, which is also the country's center of political, commercial, industrial and cultural activities.