There's free entry to the museums on 31 May to celebrate International Museum Day.

Asian Civilisations Museum
National Museum Of Singapore
NEWater Visitor Centre
NUS Museum
Memories at Old Ford Factory
Peranakan Museum
Raffles Museum of Biodiversity Research
Reflections at Bukit Chandu
red dot design museum
Republic of Singapore Air Force Museum
Singapore Art Museum
Singapore City Gallery
Singapore Philatelic Museum