Phra Nakhon Si Ayutthaya is located in the flat river plain of the Chao Phraya river valley. The presence of the Lop Buri and Pa Sak River make the province a major rice farming area.

Ayutthaya was the capital of Thailand (then called Siam) from 1350 until it was sacked by the Burmese army in 1767. This period of Thai history is now usually referred as the Ayutthaya period or Ayutthaya kingdom. The ruins of the old capital in the Ayutthaya historical park are now a UNESCO World Heritage Site. The province is also home to the Bang Pa-in summer palace complex.

According to legend King Ramathibodi I found a beautiful conch buried in the ground, and chose the site as the place for his future capital. He then placed the conch on a pedestral tray and built a pavilion around it. The seal shows this pavilion with the provincial tree behind it.
The provincial flower is Sesbania aculeata, and the provincial tree is the Fragrant Manjack (Cordia dichotoma). The provincial slogan ราชธานีเก่า อู่ข้าวอู่น้ำ เลิศล้ำกานท์กวี คนดีศรีอยุธยา can be translated as "Old capital, fertile agricultural land and fishery, excellent poetry, and good citizen of Ayuthaya".

The province is subdivided into sixteen districts (amphoe), 209 communes (tambon) and 1328 villages (muban). There are two districts which have the same English name; however this is only because the different pronunciation and thus different spelling in Thai gets lost in romanization. Ayutthaya is unique among the provinces of Thailand in that the district of its capital city is not called Amphoe Mueang [Ayutthaya], as the common scheme would suggest, but rather Amphoe Phra Nakhon Si Ayutthaya:

Information extracted from Wikipedia: Phra Nakhon Si Ayutthaya