One World Trade Center is expected on Monday to become the city's tallest skyscraper.
The webcam company EarthCam released time-lapse video of the construction.
The steel skeleton of One World Trade will reach more than 1,250-feet tall on Monday, just tipping over the Empire State Building's observation deck.
The Empire State's antenna still sits slightly higher than One World Trade, but some experts do not count antennas or flagpoles when they measure building height.
One World Trade Center will not reach its full height for at least another year. When it is complete, it will be 1,368 feet tall, or 1,776 feet tall including the antenna.