The structure was designed by Dr Edward Joseph Ryan, Superintendent of the Mount Isa District Hospital.

[1] The threat to Mount Isa seemed very real because there appeared to be little military opposition left in the north of Australia after the devastation of Darwin and the West Australian towns.

[1] Reacting to the perceived threat, Dr Edward Ryan decided to take precautions to protect Mount Isa District Hospital from air raids.

Dr Edward Ryan contacted Vic Mann, MIM Mine Superintendent, who offered the co-operation of the company and the services of Underground Foreman Wally Onton to supervise the project.

Three parallel adits were driven into the hill face and then connected to a crosscut level to form a large underground shelter with an E-shaped plan.

The excavation was timbered using the contemporary mining methods of the day, then equipped with furnishings and fittings to perform all the functions of a hospital.

Once a week there was an air raid drill, and nurses and orderlies wheeled less-seriously ill patients up the steep gravel path to the underground hospital.

History shows that Japanese resources were extended to their limit and, after the battles of the Coral Sea and Midway, their naval power was destroyed.

The shelter was used as a dormitory by the nurses on hot nights, then like most unused spaces, it gradually became a store room of hospital equipment and files.

After the war, lax security allowed young children to play in the tunnels, which still contained medical equipment and pharmaceutical supplies.

For approximately ten years the underground hospital remained closed until the fill at the north collapsed in 1977, and at the main entrance in 1988.

A public meeting in late 1995 showed that community support has swung strongly in favour of conserving and developing the underground hospital rather than again burying the entrance.

[1] Plans are in place for the interior of the hospital to be cleared by Green Corps (Young People for the Environment) and volunteer labour.

Re-timbering of the interior will be carried out under the supervision of Mount Isa Mines engineers who will also provide some of the equipment required for the project.

All the visible stone in the tunnels is a hard, light-coloured shale, which fractures along steeply dipping joint lines.

[1] All the rock surfaces in the underground hospital are slightly irregular and roughly finished, so all the following dimensions are necessarily approximate.

The north tunnel was heavily timbered with three piece sets of sawn Oregon { Douglas fir } posts and top lagged with hardwood planks resting on the caps.

There was also a considerable amount of post war material such as files, X-ray plates and medical equipment such as an autoclave.

[1] In the south tunnel there were 1940s light shades, bed tables, as well as post war material such as unidentified machinery and furniture.

[1] Throughout the underground hospital, the floor is covered with a deposit of earth, fallen stone, ash, timbers, pieces of furniture, electrical equipment and other material.

Some samples removed by firemen in 1994 contained ampoules labelled sodium glycophosphate, sulphur powder and saline solution.

The former Underground Hospital, constructed by Mount Isa Mines volunteer labour in response to the perceived threat of Japanese invasion, is thought to have been excavated between March and April 1942.

As such, the site possesses considerable archaeological significance, with potential to yield evidence about 1940s medical and nursing technology and about local improvisation during wartime.

Community concern regarding the conservation of the underground hospital is demonstrated by the number of organisations who have become involved in the conservation project, including the Mount Isa Hospital Board and City Council, the Environmental Protection Agency, and the North West Queensland branch of the Queensland Museum.