Australia's coastline is dotted with defence structures in various states of repair, a vivid testament to the threat of foreign attack at home during World War II.
From 1939 until 1945, Australia was at war with the Axis powers.
According to historians and available public records, in Western Australia alone, 645 defensive sites were placed strategically all over the state.
In Perth, Fortress Fremantle, as it is dubbed by the military, was an assortment of reinforced structures built along the coast to protect the vital deep-water port and citizens from any threat.
The history of these WWII structures is being preserved to remind us how close Western Australia came to war in its own backyard.
One of the groups endeavouring to maintain this heritage is The Royal Australian Artillery Historical Society of Western Australia (RAAHS WA), formed in 1988.
RAAHS WA president David Carter and vice president Graham McKenzie-Smith said one of the society's long-term projects had been to restore and maintain the Leighton Battery Heritage Site and its command structures, just north of Fremantle.
"All this stuff doesn't come cheap, but it's all very carefully thought out," Mr McKenzie-Smith said.
"We've followed Museums Australia practice very closely so that now we've got displays in the rooms which reflect their original intent."
As a result, the Leighton Battery, part of Fortress Fremantle, is a heritage-listed site from Australia's wartime past.
The invasion that never came
Built into a limestone hill, the Leighton Battery hosts munitions stores, secret command bunkers, and 360-degree artillery batteries with large-calibre guns on 70-tonne turntables to defend against any sea, air, and land attacks.
Those guns never had to see major action and the invasion never came.
Mr Carter said the WWII coastal defences had been worked on since about 1985, were "cleaned laboriously" and revived to offer the public an invaluable insight into our past.
The Sydney was notoriously sunk off the WA coast in 1941 near Carnarvon by the disguised German auxiliary cruiser Kormoran — a reminder of how close the enemy was to West Australian shores.
"The society was formed with the principal aim to preserve the artillery heritage of Western Australia and this is our prime asset. So, we're the curators on behalf of the Town of Mosman Park," Mr Carter said.
Popular with paranormal fans
With preservation in mind, Mr Carter said they were particularly careful about how they gave the public access to the site.
"We've put 55,000 people through in quite small penny packets because the rooms don't lend themselves to masses of busloads of tourists," Mr Carter said.
"You just can't put them through, this unique site is much more intimate than that."
And it has a broad appeal for all sorts of people.
"We have school groups, private groups, Cub Scouts, 'paranormals' [enthusiasts], they love the place as well," Mr Carter said.
A window on wartime life
Many visitors seem to appreciate the opportunity to see a window on life in wartime Perth.
"I am surprised that it's actually here. The facilities were really very interesting and worth coming to see," said tour-goer Serena after being shown around the site.
When asked about the vastness of infrastructure that still exists, another member of the public said, "I had no idea".
One of the most robust operational coastal defences in Australia at the time, the Leighton Battery was in service until 1963 when the Coast Artillery Branch of the Royal Regiment of Australian Artillery was disbanded.
The site remained in the possession of the Army and the Special Air Service Regiment (SASR) trained in the tunnels to prepare for missions during the Vietnam War with a visible splatter of bullet holes still scarring one of the walls.
Site saved
In 1979, the tunnels were handed back to the Western Australian government.
For years the site was left open to the elements and then mostly backfilled and closed to the public.
When urban development in the late 1980s could have seen it buried forever, passionate citizens appealed to the state government's Planning Department to save the site.
"But a structural engineer apparently got access into the tunnels in the early 1980s and found that they were structurally sound.
"So, I went back to the board and convinced them that the tunnels could be an asset worth preserving."
Mr McKenzie-Smith said they were able to convince the state government to consolidate the development into one area, leaving the rest of the site as public open space.
"And that's what we're standing on now. This public open space has some of the best views seawards.
"But it is now under the National Heritage Register — state and federal — so it can't be built on any longer. This forms part of what was called the Fortress Fremantle Defences."
The site became a museum and memorial that was opened in 1997.
A 'prime archaeological dig'
Mr Carter said for all the work they had done, the site still had mysteries to reveal.
As the refurbishment continued, they were still finding things, with the recent discovery of another gun pit and surrounding tunnels that were yet to be uncovered.
"We don't know in what condition it's in. It could have been completely filled in with rubble to the very top. It could be echoing empty," Mr Carter said.
