CHICAGO – Chicago city officials joined firefighters in observing a moment of silence Wednesday as the nation commemorated the 23rd anniversary of the Sept. 11 attacks.

On this day in 2001, terrorists hijacked four planes – two of which crashed into the Twin Towers, one into the Pentagon, and a fourth crashed in a Pennsylvania field after passengers fought the hijackers. The attacks killed nearly 3,000 people, including 343 emergency workers.

In Naperville, residents will gather tonight to pause and remember those who died. The city’s memorial was one of the first in the country to be erected after the attacks. It was inspired by U.S. Navy Commander Dan Shanower, a Naperville native. Shanower was working at the Pentagon on September 11, 2001, when he was killed.

Shanower, a graduate of Naperville Central High School, aspired to a career in the Navy. His words in an article, “Freedom is not free,” inspired the memorial.

Located between the DuPage River and the Naperville Municipal Building, the memorial includes a steel beam from the World Trade Center, fragments of the Pentagon and granite from Pennsylvania Field, where Flight 93 crashed after passengers thwarted an attack on the U.S. Capitol.

Tonight, Naperville will honor the victims with a ceremony beginning at 6 p.m.

“It really touches you when you have that connection to the community,” said Naperville Mayor Scott Wehrli. “We in Naperville never forget, and tonight there will be hundreds of people lining the entire waterfront who will be here to watch the ceremony and say their prayers.”

The memorial also features a 48-foot-long wall of faces symbolizing those killed in the attacks. The public is invited to attend today’s ceremony and pay their respects.