In 1969 the Fine Arts Department began with renovations of the ruins, which became more serious after it was declared a historical park in 1976. A part of the park was declared a UNESCOWorld Heritage Site in 1991. Thirty-five kings ruled the Ayutthaya kingdom during its existence. King Narai (1656 CE to 1688 CE) not only held court in Ayutthaya but also from his palace in the nearby city of Lopburi, from where he ruled 8–9 months in the year.[relevant?– discuss]
In 1991, a part of Ayutthaya Historical Park was declared a UNESCOWorld Heritage Site under criteria III as an excellent witness to the period of development of a true national Thai art. The inscribed area covered only 289 ha on central and southwest part of Ayutthaya island; as a result, only certain groups of historical sites are under UNESCO protection. The sites including Wat Ratchaburana, Wat Mahathat, Wat Phra Sri Sanphet, Wat Phra Ram and Wiharn Phra Mongkhon Bopit. The sites that are not part of World Heritage Sites are the sites outside Ayutthaya Island; for example, Wat Yai Chai Mongkon, Wat Phanan Choeng, Wat Chaiwatthanaram and Wat Phu Khao Thong.