Big difference in cities built of masonry and those built of wood. Eastern Asia had many of the largest cities through history but they were often wooden and thus much less has survived than Rome
That makes sense. Hampi and Angkor had a lot of buildings made out of stone. But what about Patna and Mathura? Ancient primary source accounts mention lots of buildings made out of stone.
Angkor Wat is not nearly as old as your Indian examples. It's similar age to Notre Dame cathedral. The main temple complex is the best preserved building in the area with some others that I think came later less well preserved. There are many many smaller temples very poorly preserved. As for a "city" of Angkor, it's now Siem Reap and there isn't much of the ancient city within the modern city.