The memorial service for the first man to walk on the surface of the moon will be held at the Washington National Cathedral on September 13 at 10 a.m. ET.
The service will be open to the public on a first-come, first-served basis, but reservations are required. Reservations must be made through NASA.
A private service was held for Armstrong in Ohio. He died on Aug. 25 from complications resulting from cardiovascular procedures.
Armstrong commanded the Apollo 11 spacecraft that landed on the moon July 20, 1969. Half a billion people watched a black-and-white TV image as he backed down the ladder of the lunar landing ship, planted his left foot on the moon's surface, and said, "That's one small step for a man, one giant leap for mankind."
The Associated Press contributed to this report.