Easily accessible by MRT, free entry. Details and history see here: http://en.wikipedia.org/wiki/Haw_Par_Villa
There used to be three such places (Singapore, Hong Kong, Fujian China): http://en.wikipedia.org/wiki/Tiger_Balm_Garden, this is the only left in its original form.
There used to be a villa on top of the hill, which was demolished shortly after WWII. A pity, signs say it had an interesting architecture and interior decoration.
Entrance to the ten courts of hell. Used to have a roof in the shape of a dragon, now bare concrete.
Copyright 2014 Christian