Historic bunkers which once offered protection during World War II now need protection of their own.

Key points: The bunkers were built during World War II

The bunkers were built during World War II They were stationed by emergency services and volunteers who ran the switchboards

They were stationed by emergency services and volunteers who ran the switchboards History groups are hoping to preserve the few that are left

South Australia is home to a handful of underground bunkers built at sports clubs, but local groups have warned they will become ruins if not properly looked after.

Why were they built?

The world was in shock when Japanese planes bombed Pearl Harbor in December 1941, forcing Australian prime minister John Curtin to join other nations and declare war on Japan.

The Australian mainland came under direct attack for the first time, as Japanese aircraft bombed towns including Darwin and Japanese submarines attacked Sydney Harbour.

Curtin warned the nation to be ready for attack and South Australia and Adelaide heeded his warnings.

Bunkers were built throughout the suburbs at Glenelg, Unley, Norwood, Prospect, Woodville, Port Adelaide and Thebarton and housed telephone networks that would relay messages back to the Bank of South Australia's underground tunnels in King William Street.

The Glenelg bunker under construction. ( Supplied: SA Water )

The bunkers were manned by emergency services, while volunteers ran the switchboards and young girls and boys were on stand-by to act as bicycle couriers.

The communication bunkers were put next to football grounds as part of overall evacuation plans should the city come under attack.

Glenelg resident Josephine Allen said people were "quite nervous".

"We had traditionally fought our wars overseas, but this was quite real to the people of Australia, people of Adelaide, that war had come to our shores," Ms Allen said.

Adelaide was in lockdown mode, with air raid shelters built in Victoria Square.

Residents were even encouraged to build their own backyard trenches to hide in, should the city be bombed.

An air raid precautions exercise with two men learning how to prop up a verandah if hit. ( Supplied: State Library of South Australia )

At risk of losing history

Ms Allen is one of a small group of people trying to preserve the suburban bunkers that were built as communications hubs during World War II.

Now, just three of the communications bunkers remain at Prospect, Thebarton and Glenelg, while another is used as an infrastructure building by the Unley council.

Neil Rossiter, from the Prospect Local History Group, has made it his mission to save the run-down and often forgotten Prospect bunker.

"If we lose our history, what do we actually tell our kids about what it was actually like," he said.

When he and other residents stepped in, the bunker was full of water and graffiti and in danger of being demolished for a dog park.

With the help of the City of Prospect, a pump was put in to take care of most of the water that came from the local water table.

The volunteers have been given some money to put up honour boards and paint a mural, but it is estimated it could cost up to $250,000 to fully restore the bunker.

"I think it will take a while, I think that council have other things in the pipeline at the moment, but that doesn't mean that we can't do something just to clean it up," Mr Rossiter said.

"Firstly get rid of the graffiti, so we can bring groups down here."

People walk by without realising hidden history

A spokesman for Prospect council said no further money would be allocated until a master plan for the precinct that also covers the Prospect Oval and Main North Road was completed.

One of Adelaide's leading magician clubs uses the Thebarton communication bunker on South Road and takes great care to maintain the historic site.

The entrance to the Thebarton bunker which is now used to conceal different kind of secrets. ( ABC News: Matthew Smith )

But it has been concerned about the long-term future.

A spokesman for the City of West Torrens said the building was heritage listed and the council was committed to its future.

Josephine Allen said part of the problem of safeguarding and improving the historic bunkers was that they were hidden.

"You have people that have lived here all their lives, have walked past it, driven by it and have absolutely no idea what it's here for or what it was and it really is a unique piece of South Australian or even Australian history," Ms Allen said.

Ms Allen, who volunteers at the Glenelg communications bunker, said it was in good condition with the support of the City of Holdfast Bay, and is open to the public.

The air raid bunker in Glenelg. ( ABC News: Matthew Smith )

She said one day she hoped it would be transformed back to how it looked during World War II.

Prospect Local History Group member David Kilner said the communication bunkers were a critical part of the past and must be protected.

"It's the old saying about those who don't remember their history are condemned to repeat it," Mr Kilner said.