Well renowned as the old capital city with the longest history of Thailand, Phra Nakhon Si Ayutthaya lasted for 417 years through the reign of 33 kings. Through these golden ages, the ancestors had left behind a wide array of priceless heritage, ranging from architecture, historical sites, archeological finds, art objects to cultural identity. Stretching across the 3,000-rai plot of land, Fine Arts Department begun the conservation for archeological sites of Phra Nakhon Si Ayutthaya under the Ayutthaya Historical Park Project in 1982. Later in 1991, the Ayutthaya Historical Park was declared as a UNCESCO World Heritage Site, along with the Sukhothai Historical Park, Si Satchanalai Historical Park and Kamphaeng Phet Historical Park, by the United Nation Educational, Scientific and Cultural Organization (UNESCO).    

Ayutthaya Historical Park consists of 425 unearthed archaeological sites, which are located within and outside the city wall, with main highlights as follows:  

The Royal Chapel, situated on the north of Wat Phra Si Sanphet on the bank of Lopburi River, is currently apparent in ruins, which were once the foundation of throne halls. Visitors will observe historical sites that were damaged by the great fire that broke out during the second defeat of Ayutthaya Kingdom. The Royal Chapel was built in the era of King Borom Trai Lokkanat as he had granted a conversion of the royal house built during the reign of King Ramathibohi I (King U-Thong) into Wat Phra Si Sanphet.     

Wat Phra Si Sanphet is considered the most important temple of Ayutthaya Kingdom. Originally, King Ramathibohi I (King U-Thong) commanded the construction of the royal house in this area in which King Borom Trai Lokkanat had later granted the use of residence as the royal temple with the aim to facilitate the operations of important royal ceremonies and merit making ceremonies. 

Wat Ratchaburana was founded by King Borom Rachathirat II (Chao Sam Phraya) in 1424 on the area used as the cremation site for Chao Ai Phraya and Chao Yi Phraya, his two elder brothers, who fought and died for a throne.

Vihara Phra Mongkol Bophit houses one of Thailand’s largest bronze Buddha images. The site is distinct with the early Ayutthaya architectural style. In 1956, Field Marshal Plaek Phibunsongkhram, the then prime minister, had commanded the renovation into the current condition. 

Furthermore, there are other archaeological sites within the Ayutthaya Historical Park, such as Wat Mahathat, Wat Phra Ram, Wat Chaiwatthanaram, Wai Yai Chai Mongkhon, Wat Phanan Choeng, Wat Thammikarat, etc.