Exeter's Nightingale Hospital is to become the first in the country to be converted into a cancer testing centre.
The hospital, one of five around the UK, has not been opened due to the South West's low rate of coronavirus.
Instead Health Secretary Matt Hancock announced it will now be converted into the testing centre, and used to help with a large number of potential cancer patients.
The hospital, originally built for those suffering from Covid-19 in the event intensive care wards were overwhelmed, will be open seven days a week, from 8am to 8pm.
It will accept its first patients on 6 July.
Sir Simon Stevens, chief executive of NHS England, told the House of Commons Science and Technology Committee that the Exeter Nightingale site will start screening multiple patients a day starting from Monday.
He claimed there would be a 'radical' change to diagnostic methods in the coming months to cope with the growing number of people waiting for tests to find out if they have cancer.
It is not the first time the hospital has undergone a change. Originally planned for Exeter's Westpoint Arena it was quickly down-sized and moved to a former Homebase store on Sowton industrial estate.
Meanwhile Bristol's NHS Nightingale Hospital - which has also not been needed - has been formally moved into standby.
The hospital, created at the University of the West of England conference centre, was to provide support for the Severn critical care network, taking in Gloucester to Yeovil and Taunton to Swindon.
NHS Hospital Nightingale Bristol will remain "ready and waiting" but staff, and resources, are now able to return to their original roles and services.
Tim Whittlestone, Medical Director, NHS Nightingale Hospital Bristol, added: "We are actively discussing with our NHS colleagues across the region how we can best use our facilities during this standby period to support their clinical and non-clinical work. Our focus is on making the best use of our resources for the benefit of all."