Banteay Kdei, built in the late 12th to early 13th century, is another of my favorite Angkor temples. I love to walk through the temple in the early morning as the sunlight filters through the roof-less corridors. If I were still a kid, I would love to play hide-and-seek in the many rooms and hallways. It just seems to be ideal for something like that. Even the meaning (Citadel of Chambers) of Banteay Kdei seems to imply as much.
For similar temples, see our posts on Preah Khan and Ta Prohm.