In your Ayutthaya tour, there is one thing that is the most popular image of local postcard you should never miss, the Wat Phra Mahathat. If that doesn't ring a bell, let's make it clear.
Wat Phra Mahathat, literally meaning "Monastery of the Great Relic", was established in around 14 century and had been serving for royal use. Following the Khmer concept of temple construction, it's a vast complex of temple platforms which houses 77 delicate stupas and a stunning77-meter-high chedi. Amongst these great works, the biggest drive for visitors is a Buddha head overgrown by bodhi tree roots all around it, peering peacefully forward, which invokes a somewhat enigmatic atmosphere.
During the long stretch of history, Wat Phra Mahathat was certainly not exempt from severe looting and damage made by foreign invaders - that's why you can see very few Buddha statues still have their heads intact. Today the temple has become a rambling site that visitors swam in for a glimpse of nostalgia and the popular Jatukhan amulets sold there.
The site is open daily from 8:00 am to 6:30 pm. Other tourist attractions you might be interested in are Wat Chai Wattanaram, Wat Mongkhon Bophit, Wat Phra Si Sanphet, and Wat Ratburana.
Now, it's convenient and popular for visitors to extend their tour to other Asian destinations by transnational flights. You may take this sample itinerary as a reference.