Complex sentence: In 1767 the city was destroyed by the Burmese army, resulting in the collapse of the kingdom, and the ruins of the old city now form the Ayutthaya historical park, which is recognized internationally as a UNESCO World Heritage Site.
Split into simpler sentences: In 1767 the city was destroyed by the Burmese army, resulting in the collapse of the kingdom. The ruins of the old city now form the Ayutthaya historical park, which is recognized internationally as a UNESCO World Heritage Site.