Many New Yorkers don't know it, but some of the world's largest public works projects are under construction right under their feet. Work is underway on extending a massive new water tunnel to keep up with demand, and workers are boring under the most dense sections of Midtown to make a new rail link into Grand Central Terminal. But perhaps the most exciting projects for city residents are two new extensions to the vast New York City Subway — one to the far West Side, and another down Second Avenue.

The Subway is New York's lifeline; it's a transportation system so vital, that the city itself wouldn't exist as we know it if the Subway were never built. And these two extensions are severely needed. City planners first started work on the Second Avenue Subway in 1929, and while the project has legendarily been stuck in a quagmire for a quarter of a century, today residents need it more than ever. And it's coming to life.

The scale of these projects is truly incredible, and what's even more amazing is that it's all happening in one of the most crowded spots on earth. And, unfortunately, as The New York Times shows in a new video in its "Living City" series, some neighborhoods have been brutally impacted by the years of construction. Foot traffic is down, dust is in the air, and construction sites mar one of Manhattan's key residential areas. The video also offers a look at how work on the new Subway line is coming along — including a shot of a massive underground explosion. Give it a watch.