The New York City subway was built by: - digging down a small amount (in contrast to London where they dug DEEP under everything else) - rerouting ALL of the

The New York City subway was built by: - digging down a small amount (in contrast to London where they dug DEEP under everything else) - rerouting ALL of the existing pipes etc (you can find photos of the rerouted gas lines) - Putting in the subway - Putting everything back