Fascinating work is going on beneath our feet, as holes are being dug in big cities that may be near you! For one, 1.7 miles of twin tunnels are in the works in San Francisco. It lies underneath existing MUNI and BART lines, and is part of a $1.5 billion light-rail extension that will be the first new subway route for MUNI in 50 years! There’s also an $800 million, three-mile tunnel in progress in Las Vegas. This one’s not transit related, but is meant to enhance the municipal water supply, so the “straw” can retrieve water when lake levels are low. Other cities with intriguing holes being developed include Seattle, Cleveland, Miami, Washington DC, and two in New York City. Of course, Los Angeles has its own rich history of tunnels.