Underneath an office building in the Otemachi business district of Tokyo is an underground rice and vegetable field. Created in a former bank vault, this hidden garden is maintained "using computer-controlled artificial light and temperature management. It was brought into being by a personnel company as a means of providing agricultural training to young people who are having trouble finding employment and middle-aged people in search of a second career." It's pretty cool, although it probably uses more energy to keep the garden healthy than it's worth if you look at what it produces. More photos at Make.
Visiting an Underground Garden Built in a Former Bank Vault Under Tokyo