Hidden New York: That's not a house

BROOKLYN, New York (WABC) -- There's a structure in Brooklyn that looks like a typical walk-up, but is far from it.

What looks like a house is actually a subway ventilator shaft for the 4 and 5 line.

Taken over by the city decades ago, it used to spew exhaust from the windows.

But recent renovations made the building look like its neighbors and the exhaust was routed to the roof.

The building is also an emergency exit for the subway line.

Click on the video above to get the full story.

Hidden New York is an exclusive abc7NY series uncovering secrets of New York City. Click here to watch more stories.