Marina Bay Sands hotel has an "Infinity Edge" pool on the ROOF -- it's kinda high up but certainly worth pushing past your fear of heights to take in the view OMG
http://www.hitfull.com/pictures/pset.php?set=Infinity_Pool_Singapore
These pools are always neat and their illusionary experience is based on relatively simple construction (https://www.google.com/search?q=infinity+edge+pool+detail+drawing&tbm=isch), but THIS baby is 200 meters above ground (http://en.wikipedia.org/wiki/Marina_Bay_Sands#Attractions) ... meh no biggie. Pics inside spoiler:
Spoiler
(http://www.hitfull.com/files/pictures/Infinity_Pool_Singapore_1.jpg)
(http://www.hitfull.com/files/pictures/Infinity_Pool_Singapore_10.jpg)
(http://upload.wikimedia.org/wikipedia/commons/a/af/2012-12-30_Marina_Bay_Sands_infinity_pool.JPG)
(http://www.hitfull.com/files/pictures/Infinity_Pool_Singapore_3.jpg)
(http://www.hitfull.com/files/pictures/Infinity_Pool_Singapore_5.jpg)
(http://www.hitfull.com/files/pictures/Infinity_Pool_Singapore_6.jpg)
(http://www.hitfull.com/files/pictures/Infinity_Pool_Singapore_11.jpg)
(http://upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Marina_Bay_Sands_during_2010_Youth_Olympics_opening.jpg/800px-Marina_Bay_Sands_during_2010_Youth_Olympics_opening.jpg)