The capsule was placed in a stone and covered with a plaque commemorating the milestone at a ceremony on Friday morning.
Port Authority Chairman Kevin O'Toole says it contains artifacts like a mask, a PATH QuickCard, facility maps, and a piece of steel from the fallen towers.
He says the agency has been through great tragedies, but it is stronger than ever.
O'Toole joked that there is no flash drive in the capsule, saying by the time it is opened in 2121, no one will know what it is, or how to use it.
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