Buildings like this were commonly seen in Cambodia, but mostly used for government establishments. Such buildings usually face east (although technically a building faces all directions), and have a spire and the little 'flares' at roof corners as you see. The spire here is a commonly photographed one, as it has a little Buddha face. This was their way of asserting that the his kind of architecture (also seen in Laos/Thailand) started with the Khmers.
This specific building is part of the Royal Palace at Phnom Penh and is called the Chan Chhaya Pavilion.
