Lopburi is famous for both it’s ancient Monasteries and Palaces as well as the monkeys that roam the city streets. And not just one or two but hundreds of them! They hang of the overhead wires, climb over the roofs and hold up the traffic when they cross the road.
And while they look pretty cute they are also known to bite if they think you have something they want. Steal cameras of unwary tourists and poop on people while sitting on the edge of a buildings roof.
On the Monastery side of the equation Lopburi is older then Ayutthaia and the architecture reflects that although here there is a large Khmer influence as well.