Patrick Cashin / MTA

April 7, 2011: With the west tunnel excavation complete, workers operating the tunnel boring machine began mining the east tunnel.

Patrick Cashin / MTA

September 2009: Second Avenue subway project

Patrick Cashin / Metropolitan Transportation Auth

October 2009: Second Avenue Subway project

By Katie Cannon, NBC News:

 A project that is 90 years in the making had better be impressive, and the Metropolitan Transport Authority's $4.5 billion Second Avenue Subway project does not disappoint.

The undertaking, which began in 2007 and can be found up to nine stories underneath the high rises of Manhattan, is the first line to be built in New York since 1932, and when completed, the initial phase will run from 96th Street down to 63rd Street. There are plans to eventually run the line all the way to Lower Manhattan.

Once there was hole large enough to venture into to photograph, MTA photographer Patrick Cashin began making pictures of the construction.

“I think when you’re down there for all of 10 seconds, you know that this is a dangerous place to be,” Cashin says. 

Despite the danger, he visits the site every few months to document the progress of this engineering feat.

For more information and an interview with Patrick Cashin, check out the Flickr blog. 

See more pictures from the MTA.

Patrick Cashin / MTA

Sept. 22, 2011: Workers completed tunneling for the first phase of the Second Avenue Subway when the project's tunnel boring machine reached the Lexington Av-63 St station, breaking into the existing subway system. The 485-ton, 450-foot-long TBM used a 22-foot diameter cutter head to mine 7,789 linear feet in two tunnels, averaging approximately 60 linear feet a day.

Patrick Cashin / MTA

January 21, 2012: Second Avenue subway project

Patrick Cashin / MTA

March 20, 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.

Patrick Cashin / MTA

March 7, 2012: 72nd Street Station cavern

Patrick Cashin / MTA

March 7, 2012: Workers use these tags to check into and out of the work site.

Patrick Cashin / MTA

March 20, 2012. Crews work in the cavern that will house the 72nd Street Station of the Second Avenue Subway.

Patrick Cashin / MTA

February 23, 2013: 86th Street Station

Patrick Cashin / MTA

March 19, 2013: A construction worker who became trapped in the mud at this location of the cavern, which will house the 96th Street station, was rescued by fellow workers and the FDNY.

Patrick Cashin / MTA

April 2013: 86th Street Station.

Patrick Cashin / MTA

April 2013: Looking up out of the construction site that will house the future 86th Street Station.

Patrick Cashin / MTA

April 2013: 86th Street Station.

Patrick Cashin / MTA

April 2013: 86th Street Station

Rehema Trimiew / MTA

May 10, 2013: 72nd Street Station

Patrick Cashin / MTA

May 18, 2013: 72nd Street Station

Mary Altaffer / AP

A contractor works on the East Side Access project beneath midtown Manhattan in New York.

Mary Altaffer / AP

Mary Altaffer / AP

Contractors work on the East Side Access project beneath midtown Manhattan, in New York. The East Side Access is one of three bold projects under New York that will expand what's already the nation's biggest mass-transit system by 2019.

Mary Altaffer / AP

Contractors work on the East Side Access project beneath midtown Manhattan in New York.

Mary Altaffer / AP

In this Tuesday, Jan. 29, 2013 photo, contractors work on the East Side Access project beneath midtown Manhattan, in New York. The East Side Access is one of three bold projects under New York that will expand what's already the nation's biggest mass-transit system by 2019.

 By Verena Dobnik, AP

Published at 3:07pm ET: NEW YORK - Sixteen stories below Grand Central Terminal, an army of workers is blasting through bedrock to create a new commuter rail concourse with more floor space than New Orleans' Superdome, just one of three audacious projects going on beneath New York City's streets to expand what's already the nation's biggest mass transit system.

But even with blasting and machinery grinding through the rock day and night, most New Yorkers are blithely unaware of the construction or the eerie underworld that includes a massive, eight-story cavern, miles of tunnels and watery, gravel-filled pits.

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Mary Altaffer / AP

Officials cover their mouths from a dust cloud created by a tunnel boring machine cutting through a solid rock wall, Thursday, Sept. 22, 2011 in New York.

Mary Altaffer / AP

A construction worker, also known as a sandhog, climbs down from a hole created by a tunnel boring machine on Thursday, Sept. 22, 2011 in New York.

Today marked an important milestone for the creation of the Second Avenue subway line in New York City. A tunnel boring machine reached the Lexington-63rd Street station, breaking into the existing tunnel that will connect it to the Q line. This marks the end of the first phase of the project.

It is nice seeing the Second Avenue line make headway. As many other New Yorkers can attest, this project felt like a myth for a long time, but it seems that shorter commutes for those along York and East End Avenues are on the way.

More on the new line on NY1.com