The head of Buddha trapped amidst the roots of a Sacred Fig Tree (ficus religiosa) in the ancient ruins of Wat Mahathat at the Ayutthaya Historical Park is probably the most iconic image associated with Ayutthaya, the former capital of Thailand. If you do a Google image search for Ayutthaya Thailand, the famous image of the Buddha head overgrown by the roots of the tree will appear several times on the first page.
Something which is significan here is that it was under the canopy of a Sacred Fig tree that Buddha found enlightenment. Throughout Thailand, you can see just how revered sacred fig trees are. They are often adorned with ribbon and have spirit houses and other Buddhist and Hindu paraphernalia placed around them. One such well known example in Pattaya is the Sacred Fig Tree in Naklua.
Exactly how the head of Buddha came to rest amidst the roots of the tree is a mystery, but Ayutthaya was over run by the Burmese in 1767, much devastation was inflicted upon Ayutthaya and the temples were not spared.
The head of the Buddha probably came to rest on the ground during the conflict, the tree which has grown nearby has aerial roots which have grown downwards into the ground and in the process have grown around the Buddha head. That’s one theory anyway.
What actually happened, how the Buddha head came to be amid the tree roots of the sacred fig tree at Wat Mahatha in Ayutthaya is actually quite simple. Around 1968–1970, a worker placed the head there after removing it from an area that was being restored, and over time the tree’s aerial roots grew down and around the Buddha head. Source: https://www.ayutthaya-history.com/wat-maha-that.html