Underground classrooms, libraries, swimming pools and even a science city for up to 4,200 workers - these are some of the proposals which have been unearthed even as studies into Singapore building downwards gather pace.
So far, the country has already engaged in several major underground projects, including a common tunnel under Marina Bay for telecommunications cables, power lines, water and refuse pipes, and the Jurong Rock Caverns for storing petroleum products.
But a host of studies are trying to see if more can be put below ground.
The Ministry of National Development is looking to see if facilities such as reservoirs, power plants and landfills can be clustered underground to save surface land.
Singapore's Central Business District, new Marina Bay Downtown and its future southern waterfront district may also be linked by an extensive underground road network beyond 2030. The Land Transport Authority is considering a plan that involves a series of subterranean ring roads.
The Building and Construction Authority's (BCA) geological office has also been studying underground rock types and conditions of sites in western and north-eastern Singapore.
The survey, which should be completed by next year, will be used to develop geological models that show the thickness, distribution and structure of the bedrock, as well as major faults in the earth.
"This will help us to identify and evaluate various land uses for potential underground developments," said a BCA spokesman.
The National University of Singapore (NUS), Nanyang Technological University and industrial landlord JTC Corporation have all recently finished exploratory studies on the possible underground developments.