Today, a tunnel below Columbia University's Morningside campus....back in the beginning of the 1900's, the Bloomingdale's Insane Asylum.
A curious network of underground tunnels connects several school building also served as a meeting place for scientists during the beginning sates of the Manhattan Project.
A few tunnels are still open to faculty and students to pass between buildings.
Spooky, hidden, but amazing!
Photo Credit: Miru Kim