Scott Townley, a retired firefighter, began building the memorial at his home in 2001, four days after the attacks. He has added to it every year since.
One section of the memorial is known as the "Octagon of Faces," displaying the faces of those killed in the attacks.
The memorial also includes a space where visitors can leave messages. The messages reflect the personal connections and memories associated with those lost in the attacks.
On Thursday, the 25th anniversary of the attacks, the small Fullerton neighborhood was expected to become a gathering place for the broader community. The street was scheduled to close at 6 a.m. as volunteers, firefighters and police prepared for a ceremony beginning at 8:30 a.m.
Local students, families of some victims and community members were expected to attend. Organizers planned to read aloud the names of all 2,977 people killed in the attacks.
Townley said he hopes the memorial helps younger generations understand the human impact of Sept. 11.
Three-quarters of Americans say they remember where they were when they heard about the attacks, while another 11% of the country was not yet born. For many students attending the event, Sept. 11 is not a personal memory but a historical event.
Townley's goal, organizers said, is to ensure that future generations remember the people behind the tragedy.