The NHS Nightingale Hospital set up inside Birmingham's National Exhibition Centre (NEC) is now operational, it has been confirmed.
Initially built with a 500-bed capacity, it can be increased to 1,500 or more if needed.
It is designed to take coronavirus patients from 23 Midlands hospitals, if units cannot cope with demand.
Two further Nightingale Hospitals are also being planned for Sunderland and Exeter.
Despite being ready to take patients if needed, only staff training and cleaning was taking place at the site in the West Midlands on Friday, University Hospitals Birmingham NHS Trust (UHB) confirmed.
Dr David Rosser, chief executive of the trust which is leading the hospital, said: "We would all prefer that these beds - just like the extra beds the NHS has freed up across the region - are needed as little as possible, and so we would continue to urge members of the public to stay at home to help NHS staff save lives."
We're welcoming hundreds of #NHS colleagues from Trusts across the region to the hospital today for our first induction. Thank you to all those who are joining us to care for those affected by #COVIDー19 over the coming weeks. pic.twitter.com/32XWiOKgwG— NHS Nightingale Birmingham (@NightingaleBham) April 9, 2020
In a post on Twitter, Conservative mayor Andy Street said putting together the Birmingham facility in under two weeks had been a "Herculean effort".
"However despite the accomplishment, my hope is actually that it is hardly ever used," he added.
"Patients will only be admitted when our existing hospitals start to reach capacity, and currently, they are coping very well with demand and have sufficient critical care space available."
A 460-bed Nightingale Hospital is being built in an industrial unit in Washington, Tyne and Wear.
The site, owned by Sunderland City Council, close to the A19, will be divided into 16 wards.
While chief nursing officer Ruth May announced another was to be opened in Exeter.
Sharon Hodgson. MP for Washington and Sunderland West, said the dedicated facility would "help save lives and will take some of the pressure off local hospitals, such as Sunderland Royal, South Tyneside District Hospital, the QE in Gateshead and Newcastle hospitals, and ensure that local people are cared for locally".
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