While above ground New York's One World Trade Centre might be grabbing all the headlines, beneath the streets of the city there is an even bigger feat of engineering underway.
The Second Avenue Subway is finally being built after a hefty 90 years of planning and delays.
It is the first subway to be constructed in New York since 1932 and will ease public transport congestion on the east side of Manhattan.
Its total cost will be a whopping $4.5 billion (£2.85 billion).
Photographer Patrick Cashin has been documenting the project.
He said: "When I arrived on the scene in 2009, it was just a lot of mud and dirt, but as I kept going back, this hole kept getting deeper and deeper and soon it extended several blocks.
"What’s really impressive is when you walk through where the tunnel boring machine had cut the 22-foot hole.
"And and then BOOM, you’re in this huge cavern. It’s this huge hole where the 72nd Street Station is going to be, and it just hits you how big, how much digging they had to do to get this cavern made. It’s just amazing."
Story continues after slideshow...
One of a set of photos showing the status of progress on the Second Avenue Subway tunnels and caverns as of January 21, 2012
Nine stories underneath the streets of Manhattan's East Side, workers are building the cavern that will house the 72nd Street Station of the Second Avenue Subway
These photos show the status of construction on the Second Avenue Subway's 72nd Street Station cavern as of March 7, 2012
This is an update showing the progress on construction of the the Second Avenue Subway as of Saturday, May 12, 2012
Construction continues on the Second Avenue Subway's future 86th Street Station. This photo shows the latest progress as of April 2013
Construction is proceeding on the future 72nd Street Station of the Second Avenue Subway. This photo shows progress as of May 18, 2013.
Second Avenue Subway retrospective: This photo is from October 2009
Excavation work on the cavern that will house the Second Avenue Subway's 86th Street Station continues as of February 23, 2013
This photo shows the progress of construction on the Second Avenue Subway project's 72nd Street Station cavern and tunnels leading south as of Sept. 22, 2012
The excavations have not been without their controversies (see the video below).
The project is reminiscent of London's very own Crossrail project...