Changi Airport was built because the government decided in 1975 to build a new airport at the eastern tip of the main island at Changi, at the existing site of Changi Air Base, where the new airport would be easily expandable through land reclamation. This happened because the current airport at that time, the Seletar Airport and Paya Lebar were located at places with potential urban growth and so the government decided to built the new airport at a secluded area.
It started of with only 1 terminal until in 1990, the second terminal was opened and it attracted even more customers. Terminal 3 was then finally opened in 2008 which included a hotel and an area specially for shoppers.
Here are some pictures and videos of the Changi Airport.