Today's OneWord: Underground

The Underground had been designed to be just that - buried deep in the earth so that little light came, but water still flowed easily, the pipes in remarkable condition considering that the plumbing itself was over fifty years old. Paths and tunnels had been carved through both hard rock and rich,  soft soil, and beneath your feet, you could barely feel the warmth of what must of been lava underneath: "Our natural heating system," the mayor said.