Ground penetrating radar is a technology that doesn't work very well apparently. http://www.newyorker.com/magazine/2015/08/03/underworld-monte-reel http://www.

Ground penetrating radar is a technology that doesn't work very well apparently. http://www.newyorker.com/magazine/2015/08/03/underworld-monte-reel http://www.newyorker.com/magazine/2015/08/03/underworld-mont...