overlay theory

History is full of examples of situations where civilizations have built new structures directly on top of existing structures, sometimes even leaving space for the existing structures as if they could someday be used again.

One such example would be the old tunnels that run beneath many of our American cities. Some were utility tunnels, some were trolley routes, overpaved streets, and others have mysterious origins. I find it intriguing that many still exist to this day, and are accessible to those who know how to find them (albeit illegally in many areas).

I remember seeing a television show once that covered the catacombs of France - hundreds of miles of tombs and labyrinths to be explored by brave thrill-seekers. It is a major source of tourist revenue for them. Meanwhile, many cities in America have similar (but not quite as grand) tunnels of the past hiding beneath our feet - beneath our traffic and unassuming pedestrians. So why not analyze the foundations of these tunnels, re-support and/or ventilate them as needed and offer tours through them? It seems like a no brainer to me. Here we are, with a "goldmine" (or at least a mine-type corridor) of potential revenue sitting right under our noses.

Sure, there are liabilities to consider, and some would be too dangerous, but many of these tunnels and thoroughfares were built to last in true "old school" fashion - for the long haul. Why not provide that unique glimpse into history to those who are unafraid?