At this captivating ruined temple, three wonderfully intact stupas form one of Ayuthaya's most iconic views; unlike at many other ruins, it's possible to clamber up the stairs for a lofty vantage point (and epic selfie). Built in the late 15th century, this was a royal temple inside palace grounds; these were the model for Bangkok's Wat Phra Kaew and Royal Palace. This temple once contained a 16m-high standing Buddha (Phra Si Sanphet) covered with at least 143kg of gold.
The gold from the statue was melted down by Burmese conquerors.
A trove of Buddha statues discovered here are now displayed in Bangkok, while wooden door panels from the stupa can be viewed locally at the Chao Sam Phraya National Museum.
You can visit Wat Phra Si Sanphet using Ayuthaya's 220B multi-temple ticket. It's south of the Old Royal Palace.