Historic photos of Christchurch from above have been revealed.

A selection of snaps from one of New Zealand's biggest photo archives has revealed Christchurch's changing cityscape.

The Air Force Museum of New Zealand displayed nine historic aerial photos of the city for Heritage Week, chosen from over 1 million negatives in its photographic archives.

The photos were shown at the Be a Time Traveller exhibit at the Arts Centre last Sunday.

1 of 17 Royal New Zealand Air Force The centre of Christchurch in January 1918 - the oldest photo the Air Force Museum of New Zealand provided. 2 of 17 Royal New Zealand Air Force Christchurch city in the 1920s. Note Christ's College and the Botanical Gardens at the bottom left. 3 of 17 Royal New Zealand Air Force Cathedral Square in September 1928. Image from the J.L. Findlay personal album collection. 4 of 17 Royal New Zealand Air Force Cathedral Square and part of Victoria Square in 1930. 5 of 17 AIR FORCE MUSEUM OF NEW ZEALAND Christchurch Boys' High School, circa 1930. 6 of 17 Royal New Zealand Air Force The middle of Christchurch in 1939. Image from the R.W. Russell personal album collection. 7 of 17 Royal New Zealand Air Force Three Avro 626 trainer planes in formation over the Port Hills, with Quail Island and Lyttelton Harbour behind. Circa 1939. 8 of 17 Royal New Zealand Air Force Three Harvard trainer airplanes in formation over South Brighton spit, flying from Royal New Zealand Air Force Station Wigram in July 1941. 9 of 17 AIR FORCE MUSEUM OF NEW ZEALAND Harvard NZ944 over Christchurch, circa 1944. 10 of 17 Royal New Zealand Air Force A snow covered central Christchurch in July 1945. About 45 centimetres of snow fell on the city on July 14, 1945. 11 of 17 Royal New Zealand Air Force Cathedral Square on November 19, 1968. 12 of 17 Royal New Zealand Air Force Central Christchurch, November 1968. 13 of 17 Royal New Zealand Air Force Paparua Prison, now called Christchurch Men's Prison, in the 1970s. 14 of 17 AIR FORCE MUSEUM OF NEW ZEALAND A De Havilland Devon above Lyttelton, September 28, 1972. 15 of 17 Royal New Zealand Air Force Cathedral Square, September 8, 1975. 16 of 17 Royal New Zealand Air Force Airtrainer NZ1733 and Harvard NZ1015 in formation over Lyttelton, February 14, 1977. 17 of 17 Royal New Zealand Air Force The meatworks complex in Belfast, October 10, 1978.

Air Force Museum communications officer Michelle Sim said the exhibited images reflected the close connection the Royal New Zealand Air Force had with the city of Christchurch, through 70 years of aviation activity out of Wigram.

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AIR FORCE MUSEUM OF NEW ZEALAND Christchurch Boys' High School and the area looked very different in 1930.

The Heritage Week display tried to show how that connection was not confined to Wigram, but engaged with the wider city, she said.

"A lot of people don't realise how important that air force base was to Christchurch."

Air Force Museum keeper of photographs Matthew O'Sullivan said the museum's collection was nationally important because of the aerial photos it held, which showed how New Zealand had changed over time.

Before and during World War II, there "weren't really a lot of aircraft around" outside of the Air Force to do that type of work.

The collection focuses on New Zealand, but subjects range from the Auckland Islands in the south to "way up to the equator" in the Pacific, and includes photos from as early as 1918.

Only "a tiny percentage" of the collection has been scanned to digital so far – about 5000 photos in high resolution – as it takes a few minutes to scan each negative.

O'Sullivan said the photos were used by a wide range of people and groups, such as authors, historians, archeologists, and academics.

There often was not much information about why the older photos were taken and it could be up to researchers to "interpret that history", he said.

"If the information hasn't survived or was never recorded, there's not much else we can do."

Wigram Air Force Base closed in 1995, after operations were moved to the Ohakea base. The Air Force Museum of New Zealand is on the old base.

Heritage Week runs from October 14 to 24, with a range of activities and exhibitions being held across the city. The theme this year is 'hidden histories – our stories unearthed'.