Here's how Manhattan's skyline has changed in the 25 years since the 9/11 attacks

The Tribute in Light was tested ahead of the 25th anniversary of 9/11.

Adam Gray/Getty Images

Each September, two large beams of light reach into the night sky above Manhattan's Financial District.The installation commemorates those who were killed on September 11, 2001.This Friday marks 25 years since that day, when terrorists hijacked four commercial passenger planes, crashing two into New York's Twin Towers.Another plane hit the Pentagon in Arlington County, Virginia, and the fourth crashed into a field in Shanksville, Pennsylvania, after passengers attempted to overpower the hijackers.In total, 2,977 victims lost their lives and, more than two decades later, their loved ones continue to gather to recite their names at the 9/11 Memorial at the World Trade Center complex in New York.These photos show how the attacks destroyed the towers that once defined the city's skyline, and how New York rebuilt Ground Zero.

The Twin Towers dominated the New York City skyline on this June day in 1999.

The Twin Towers in New York City in June 1999.