Take A Look Inside The Cavernous Construction Zone Below Grand Central Terminal

Metropolitan Transportation Authority / Patrick CashinNew York City, which already has the country's largest mass transit system, is in the midst of an ambitious $8.3 billion development project to build a new concourse beneath Grand Central Terminal.

The construction site, located 16 stories below the station, will grant the Long Island Rail Road access to Manhattan's East Side. Currently, Penn Station is the exclusive location of the LIRR in Manhattan.

When it's completed in 2019, the new station will bring in an estimated 160,000 Long Islanders each day, according to the AP.

But for now it's an astoundingly large construction site, standing eight stories high and with six miles of tunnels in the works. The MTA periodically releases construction photos on its Flickr page; here are some highlights from the latest batch.