There are several Angkors (Khmer kingdoms) spread over a 50 sq mile site in Siem Reap. I will give you a brief visual insight here - there's just too much to explain what/how/where/why, so there will be no descriptions with the images - and I wouldn't do justice to the place.

To really appreciate the grandeur of the medieval Khmer empire, you need to be reasonably familiar with the history also. The ultimate treat is to visit the place yourself - you'll never regret it - it's a one in a lifetime 'must-do'.