NEW YORK (AP) — The World Trade Center’s newest skyscraper has reached its full height of 80 stories.

About 1,000 workers attended the topping out of 3 World Trade Center in New York City on Thursday morning. They signed a mammoth bucket holding 2 tons of concrete that’s being hoisted to the top of the $2.5 billion high-rise to signal the construction milestone.

The building is one of three new skyscrapers that replace the twin towers destroyed in the Sept. 11, 2001, attacks.

The others are 4 World Trade Center and One World Trade Center — the main building of the rebuilt site. One more is planned, 2 World Trade Center. Only its foundation is built.

Some of the workers invited to Thursday’s ceremony helped to clean up after the 9/11 attacks.