Wake the Bat

The underground tunnel system, located underneath the sidewalks and streets of almost every major town and city in Colorado was not a new concept. The first known underground tunnels were built around 4,000 BC in Babylonia and the concept expanded to the Egyptians and onto the Romans, as they conquered the then known World. An underground vault is constructed as part of the basement of a building and can expand under the street or even cross over to the other side.