Imogenia International Airport was opened in September 1978. The original construct, Terminal 1, has been heavily modified and now consists of a central terminal and four semi-autonomous piers (A-D). The original twin central piers (B & C) have been extended and rebuilt (reopening in 1985 & 1989 respectively). Pier A, on the eastern side, was extended in 1987 while Pier D gained a large satellite terminal extension, which opened in 1994.
Within Terminal 1 all of the piers (except the majority of Pier D) are joined by a single multi-track monorail system which transits passengers both within and outside of the main terminal buildings.
Between 1991 and 1995 Terminal 2 was constructed on a site to the east of Terminal 1. The original north facing runway (36) is to be joined by a second runway scheduled to open in 1999.
There are, depending on gate utilisation, between 56 and 58 gates available at IMO. Swing gates on Pier C account for the variation. All 56 standard gates are served by airbridges.
Singapore Airlines (SQ) and its Star Alliance partners make up the primary traffic at Piers 1A and 1B. Pier 1C is the domain mainly of Chinese carriers and Malaysian Airlines (MH) whilst 1D takes most of the rest and any Skyteam aligned carriers. Terminal 2 is the home of airlines in the Oneworld alliance, particularly Cathay Pacific (CX).
| PIER | NO OF GATES | GATE NOS |
| Pier 1A | 6 | A1-A6 |
| Pier 1B | 12 | B7-B18 |
| Pier 1C | 12-14 | C19-C30 |
| Pier 1D | 15 | D31-D45 |
| Terminal 2 | 11 | 201-211 |
| CLASS | LARGEST AIRCRAFT | NO OF GATES |
| E(ii) | 747 | 38 |
| E(i) | MD11 | 4 |
| D(ii) | 767 / DC10 | 10 |
| D(i) | 757 / A310 | 4 |