Dallas has about three miles of subterranean tunnels and sky bridges that crisscross the city, but aside from a few food courts beneath office highrises, they're largely vacant. If that's the case, why are they there in the first place? And what is the future of the empty space?

Baylee Friday gets a tour of the tunnels from Dallas software developer Michael Sitarzewski, who took an interest in them and knows every nook and cranny. Then, Dustin Bullard, chief of urban transformation for Downtown Dallas Inc., and Dallas City Council member Paul Ridley, whose district includes most of the tunnels, explain the vision for downtown and whether the underground space has a place in it.