Better known as Krungsri Walking Street or Krungsri Night Market by locals, this night market does not take place every day but only takes place on weekends. It is probably one of the most beautiful night markets in Thailand with its illuminations and bamboo tables and stands near an L shaped pond, the Bueng Phraram. You will mostly find to eat and drink but also some stalls selling other products and souvenirs. There are also small shows including demonstrations traditional martial arts.
It's really a nice place to go in the evening in Ayutthaya to discover the local cuisine and to taste a lot of small snacks or dishes. I strongly encourage you to take a tour.