Outram Park MRT Station was created in 1987.
Farrer Park MRT Station was created in 2003.
You could hire a taxi (the more expensive but more comfortable option). You could also take the train from Changi Airport till Outram Park MRT station. Then change trains to the Purple line and take it from Outram Park all the way to Harbourfront MRT station. (take note: you will have to walk quite a bit to change trains, but is a covered link)
Aljunied MRT Station was created in 1989.
Chinatown MRT Station was created in 2003.
Guadalupe MRT Station was created in 1999.
Buangkok MRT Station was created in 2006.
Bayfront MRT Station was created in 2012.
Lavender MRT Station was created in 1989.
Serangoon MRT Station was created in 2003.
Dover MRT Station was created in 2001.
Santolan MRT Station was created in 1999.
Yishun MRT Station was created in 1988.