Chao Phraya River

Boat is the way to do this. Ayutthaya sits on the river, and half the ruins along the banks make far more sense from the water than they do from the back of a tuk-tuk. Crumbling spires, wooden houses on stilts, people getting on with their day. The old capital's merchant routes and royal processions used the same stretch of water, and the layering of all that is the point of the trip.

Time of day changes the whole thing. Mornings are quiet and slow, good if you want to sit and look rather than tick off sites. Sunset is busier, and it's when the light hits the stone towers properly, so that's the run photographers should book. Don't try to cram it between three temples and a museum. Rushing the river defeats the purpose.