It was the climax of a giant Apollo moon-landing operation that began 12 years ago and cost $22,501 million.
A television camera positioned at the bottom of the spacecraft's ladder recorded the scene as Armstrong's ghostly figure emerged from the spacecraft and was guided down by his companion inside.
Armstrong's first words as he gingerly slithered his feet across the moon's surface were: "That's one small step for man, but one giant leap for mankind."
Armstrong was joined on the moon's surface by Aldrin 20 minutes later.
PEACEFUL MISSION
Together they unveiled a plaque and planted the American Stars and Stripes.
The plaque said simply: "Here men from the planet earth first set foot upon the moon, July 1969 A.D. We came in peace for all mankind."
With no breeze to keep it flying, the flag had a stiffener along its top edge to keep it unfurled.
Then, as the astronauts scoured the moon's surface, the secrets came tumbling out.
Armstrong reported: "The surface is fine and powdery. It adheres like powdered charcoal to my boot ... I go in only an eighth of an inch."
The television cameras panned across the pimply, rock-strewn and cratered surface, and Armstrong said it reminded him of some desert territory in the United States.
"But it has a beauty of its own ... It's very pretty up here," he added.
BLEAK WORLD
Outside their vehicle the astronauts found a bleak world. It was just before dawn, with the sun low over the eastern horizon behind them and the chill of the long lunar nights still clinging to the boulders, small craters and hills before them.
Aldrin said that he could see "literally thousands of small craters" and a low hill out in the distance.
But initially, he was impressed most of all by the "variety of shapes, angularities, granularities" of the rocks and soil where the landing craft had set down.
"The surface is fine and powdery. I can pick it up loosely with my toe. It adheres like powdered charcoal to my boot."
"Ready for me to come out?" Aldrin asked at 3.10 p.m.
"OK, you saw what difficulties I was having," Armstrong told Aldrin as he guided him out of the ship's hatchway.
Aldrin said that it was hard to tell whether some of the objects on the moon were clods or rocks.
"It bounces," he said, apparently kicking an object.
Aldrin's first words on stepping down to the moon were: "Beautiful, beautiful, beautiful. A magnificent desolation."
Mission control had to remind Armstrong to pick up the moon contingency sample. It had to be picked up immediately in case he and Aldrin had to get back to the ship in a hurry.
The astronauts seemed to bounce about as they walked around the space craft.
"You've got to be careful you lean in the direction you want to go, otherwise you seem inebriated," one said.
With oxygen packs strapped to their backs, giving them about three hours of life on the moon, the astronauts went about their work with the calmness of a Sunday afternoon gardener on earth.
They set up on the moon instruments that will continue to give scientists on earth information for some time to come.
Nearly nine hours after landing, the astronauts were still busy, filling containers with samples from man's new world.
At 4.53 p.m. ground control ordered Aldrin to "close out his E.V.A. (extra vehicular activity)"; meaning prepare to return to Eagle.