WASHINGTON (CNN) -- The first man on the moon marked the 40th anniversary of his historic achievement with characteristic understatement Monday, calling the program that put him on the lunar surface "a good thing to do." 

President Obama welcomes, from left, Buzz Aldrin, Michael Collins and Neil Armstrong. 

Apollo 11 commander Neil Armstrong joined crewmates Michael Collins and Buzz Aldrin at the National Air and Space Museum, capping a day of commemorations that included a stop at the White House. During brief remarks at the museum, he said the mission was the climax of a "staggeringly complex" endeavor that "required the very best in creativity, determination and perseverance that could be assembled in the American workplace." 

"Those successes were very impressive 40 years ago, but they were not miraculous," Armstrong said. "They were the result of the imagination and inventive minds of the people in the Apollo project since its inception eight years earlier." 

The July 20, 1969, moon landing followed four test missions and came just two years after a fire that killed the first Apollo crew. Six lunar landings followed. A seventh flight, Apollo 13, was forced to abort its landing after an oxygen tank explosion crippled the spacecraft; the crew used its lunar lander as a "lifeboat" for much of their harrowing return to Earth. 

Armstrong called the Apollo program "a superb national enterprise" that "left a lasting imprint on society and history." 

"Our knowledge of the moon increased a thousandfold and more," he said. "Technologies were developed for interplanetary navigation and travel. Our home planet has been seen from afar, and that perspective has caused us to think about its and our significance. Children inspired by the excitement of space flight have come to appreciate the wonder of science, the beauty of mathematics and the precision of engineering." 
Who was the Apollo 11 commander?
What 2 crewmates joined him?
Where were they?
What were they doing there?
Did they make any stops?
Where?
Who welcomed them there?
How many year anniversary is this?
What did Armstrong say at the museum?
What was the date of the moon landing?
What did it follow?
What happened 2 years after that?
How many more landings were there?
What happened to the 7th?
What was the name of that mission?
Why did they have to abort?
What did they use as a lifeboat?
Did they make it back to Earth?
What does Armstrong call the Apollo program?
How much did he say our knowledge of the moon has increased?
Neil Armstrong
Apollo 11 commander Neil Armstrong
Michael Collins and Buzz Aldrin
Neil Armstrong joined crewmates Michael Collins and Buzz Aldrin
at the National Air and Space Museum
Neil Armstrong joined crewmates Michael Collins and Buzz Aldrin at the National Air and Space Museum
commemorating the 40th anniversary of the moon landing
the 40th anniversary of his historic achievement with characteristic understatement Monday, calling the program that put him on the lunar surface "a good thing to do." 

President Obama welcomes, from left, Buzz Aldrin, Michael Collins and Neil Armstrong. 

Apollo 11 commander Neil Armstrong joined crewmates Michael Collins and Buzz Aldrin at the National Air and Space Museum, capping a day of commemorations
Yes
capping a day of commemorations that included a stop at the White House.
at the White House
a stop at the White House
President Obama
President Obama welcomes, from left, Buzz Aldrin, Michael Collins and Neil Armstrong.
40th
The first man on the moon marked the 40th anniversary of his historic achievement
the mission was the climax of a "staggeringly complex" endeavor that "required the very best in creativity, determination and perseverance that could be assembled in the American workplace. Those successes were very impressive 40 years ago, but they were not miraculous. They were the result of the imagination and inventive minds of the people in the Apollo project since its inception eight years earlier."
he said the mission was the climax of a "staggeringly complex" endeavor that "required the very best in creativity, determination and perseverance that could be assembled in the American workplace." 

"Those successes were very impressive 40 years ago, but they were not miraculous," Armstrong said. "They were the result of the imagination and inventive minds of the people in the Apollo project since its inception eight years earlier."
July 20, 1969
The July 20, 1969, moon landing
four test missions
The July 20, 1969, moon landing followed four test missions
a fire killed the first Apollo crew
came just two years after a fire that killed the first Apollo crew.
Six
Six lunar landings followed.
it was forced to abort its landing
A seventh flight, Apollo 13, was forced to abort its landing after an oxygen tank explosion crippled the spacecraft
Apollo 13
A seventh flight, Apollo 13
an oxygen tank explosion crippled the spacecraft
was forced to abort its landing after an oxygen tank explosion crippled the spacecraft
its lunar lander
the crew used its lunar lander as a "lifeboat"
Yes
the crew used its lunar lander as a "lifeboat" for much of their harrowing return to Earth. 
"a superb national enterprise"
Armstrong called the Apollo program "a superb national enterprise"
A thousandfold and more
"Our knowledge of the moon increased a thousandfold and more,"