Thailand's King Bhumibol, the world's longest-reigning monarch, turns 85 Royal Guards parade ahead of an address by Thai King Bhumibol Adulyadej at the Anantasamakom Throne Hall in Royal Plaza in Bangkok's historic district. Tens of thousands of Thais crowded Bangkok for a rare address by King Bhumibol Adulyadej, the world's longest reigning monarch, as part of celebrations for his 85th birthday.