No one was hurt, but witnesses said they heard a loud bang when the window fell around 11 a.m. on West 38th Street in Midtown.
It's not clear what caused the window to fall, but there is a construction site next door.
A hotel is being built there.
A worker was sweeping up shattered glass on the sidewalk.
Firefighters were on scene taking apart the glass from the frame that remains, to prevent anything else from falling.
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