It is 50 years since the Apollo programme put human feet on the Moon.
Perhaps what's most remarkable is that no human has returned to the lunar surface since.
The Apollo programme started in 1961 and ran until 1968, and it's difficult to comprehend how so much was achieved in so short a time.
According to the official report to congress in 1973, the Apollo programme cost $25.4 billion (approximately £20 billion). In today's money that equates to over $167 billion (£131.6 billion).
It was the third US human spaceflight programme carried out by NASA, employing over 400,000 people.
Images of Apollo astronauts on the Moon are well known. Our gallery includes images that show what life was like for those involved in the Apollo missions, both behind the scenes and on the world stage.
Lunar landing testing, 18 June 1965. Here, NASA test the landing procedures of a lunar module. The 75m high and 122m long gantry structure became active in 1965 and was used extensively during the Apollo programme. Credit: NASA
Reduced gravity simulation, 3 June 1965. NASA used devices like this Reduced Gravity Simulator to observe the effect of reduced gravity on movement. Astronauts practised walking in conditions that felt like one sixth of the gravity on Earth. Credit: NASA
Poolside training,
June 1966. The crew of Apollo 1 practice water egress training at Ellington Air Force Base, Houston, Texas. On the life raft in the foreground is astronaut Edward H White II. Roger B Chaffee can be seen climbing out of the boilerplate spacecraft, whilst Virgil I Grissom is still inside. Credit: NASA
Apollo 9 Lunar Module, 8 March 1969. During the fifth day of Apollo 9 Earth-orbital mission, the Command Module photographs the Lunar Module "Spider" against the backdrop of space. Credit: NASA
No small step, 9 July 1969. When planning to land on the Moon, NASA were not sure how deep the Moon dust would be. There was a possibility that when Neil Armstrong took his first step he might sink irretrievably. Training sessions prepared him for a big step back onto the Lunar Module ladder. Credit: NASA
Presidential spectators, July 16, 1969. Surrounded by a crowd of enthusiastic onlookers, US Vice President Spiro T Agnew (right) and former US President Lyndon B Johnson (left) watch the Apollo 11 launch. Credit: NASA
Apollo 11 spectators assemble, July 16, 1969. Pictured is a snippet of the crowds that gathered on roadsides and beaches close to NASA Kennedy Space Center to watch the Apollo 11 launch. Many had camped the night before to ensure they secured a good spot. Credit: NASA
Houston, we have lift-off, July 16, 1969. The Saturn V soars skyward carrying the precious Apollo 11 payload. In 2.5 minutes the S-IC booster lifts the rocket to an altitude of about 62km. Apollo 11 is officially underway. Credit: NASA
First steps, 20 July 1969. Following closely in the footsteps of Neil Armstrong, Edwin (Buzz) Aldrin takes his first steps on the Moon. Credit: NASA
Mission recovery, July 24, 1969. US President Richard Milhous Nixon (centre) watches the recovery of the Apollo 11 Lunar Mission, aboard the USS Hornet aircraft carrier. Standing next behind Nixon (right of the image) is astronaut Frank Borman, Apollo 8 Commander. Credit: NASA
Long-awaited reception, 27 July 1969. The Apollo 11 crew are greeted by their wives (L-R) Pat Collins, Jan Armstrong and Joan Aldrin, upon arrival at Ellington Air Force Base. The crew (L-R) Armstrong, Aldrin and Collins are still under their 21-day quarantine period. Credit: NASA
Apollo 11 New York jubilations, 13 August 1969. The whole of New York City comes out to welcome the Apollo 11 crew, showering them in ticker tape. Pictured in the car, from right, are Neil Armstrong, Michael Collins and Buzz Aldrin. Credit: NASA
Landing practice, 25 October 1969. Lunar simulation flight at Ellington Air Force Base. Test flights were key in teaching astronauts what to expect from their Lunar Module when landing on the Moon. Here, astronaut Charles Conrad Jr, commander of Apollo 12 demonstrates his landing skills. Credit: NASA
Lunar surface exploration, 14 - 24 November. Apollo 12 was designed to carry out a number of lunar soil activities including the collection of 34kg of rock samples. This image was taken during the mission, showing the lunar surface and the footprints of the astronauts in the dust. Credit: NASA
Pacific recovery, 24 November 1969. The recovery of the Apollo 12 mission, the second manned mission to the Moon. Apollo 12 astronauts were Lunar Module pilot Alan L Bean, Command Module pilot Richard Gordon and Commander Charles Conrad. All three can be seen in the life raft. Credit: NASA
Sub-aqua astronaut, 17 January 1970. Astronaut Thomas K Mattingly II, Command Module pilot of Apollo 13, carries out water egress training at the Manned Spacecraft Center. Training like this is prepared astronauts for a water landing, coping with a capsized spacecraft and remaining calm under pressure. Credit: NASA
Special viewing, 14 April 1970. Marilyn Lovell, wife of Apollo 13 astronaut James A Lovell chats with Dr Charles A Berry, Apollo 13 flight surgeon. Shortly after this image was taken, an explosion in the Service Module caused the cancellation of the lunar landing phase of the mission. Credit: NASA
Tensions are high, 16 April 1970. Mission Operations Control Room of the Mission Control Center during the final 24 hours of Apollo 13. When this photo was taken, Apollo 13 crewmembers were in trans-Earth trajectory, attempting to bring the problem-plagued spacecraft home. Credit: NASA
Splashdown success, 17 April 1970. Staff members from NASA Headquarters Manned Spacecraft Center and Dr Thomas Paine (centre of frame) applaud the successful splashdown of the Apollo 13 mission in the south Pacific Ocean, while Dr George Low smokes a celebratory cigar (right). Credit: NASA
Catch of the day, 17 April 1970. Astronaut James A Lovell Jr. is hoisted to safety after Apollo 13 mission splashdown. Lovell was the last of the three Apollo 13 crew members to exit the Command Module and be lifted to safety. Credit: NASA
Read all about it, 17 April 1970. Astronaut James A Lovell Jr, Apollo 13 mission commander, reads a newspaper article about the safe recovery of the problem-plagued mission. Credit: NASA
Apollo 14 lift-off, 31 January 1971. The Saturn V rocket carries Apollo 14 Mission Commander Alan B Shepard Jr, Command Module pilot Stuart A Roosa and Lunar Module pilot Edgar D Mitchell. Apollo 14 was the third manned lunar landing mission. Credit: NASA
Lunar locomotion, 1 August 1971. The Lunar Roving Vehicle photographed on the Moon during the third Apollo 15 lunar surface extravehicular activity at the Hadley-Apennine landing site. Credit: NASA
Lunar Module pilot James B Irwin gives a military salute during at the Hadley-Apennine landing site, on the Apollo 15 mission. The Lunar Module 'Falcon' is in the centre of the image and on the right is the Lunar Roving Vehicle. Credit: NASA
Test drive, 6 September 1972. Apollo 17 Commander Eugene A Cernan (foreground) and Lunar Module pilot Harrison H Schmitt (on Cernan's right) take the Lunar Roving Vehicle trainer for a spin in the Pancake Range area of south-central Nevada. Credit: NASA
Right-side up, 17 December 1972. Apollo 17 was the final lunar landing mission in NASA's Apollo programme. Here Lunar Module pilot Harrison H Schmitt takes a photo of crewmembers Eugene A Cernan and Astronaut Ronald E Evans. This is one of the last images taken on an Apollo mission. Credit: NASA
The final descent, 19 December 1972. The Apollo 17 Command Module, with astronauts Eugene A Cernan, Ronald E Evans and Harrison H Schmitt aboard, nears splashdown in the south Pacific Ocean, successfully drawing the Apollo programme to a close. Credit: NASA
