Prince Charles has remotely opened a a new temporary hospital at London's main exhibition and conference centre.
The Nightingale Hospital will soon be able to treat 4000 people who have contracted COVID-19.
Recovered from coronavirus himself, Charles said he was "enormously touched" to be asked to open the temporary facility at the ExCel centre in east London.
He paid tribute to everyone, including military personnel, involved in its "spectacular and almost unbelievable" nine-day construction.
"An example, if ever one was needed, of how the impossible could be made possible and how we can achieve the unthinkable through human will and ingenuity," he said via video link from his Scottish home of Birkhall on Friday.
"To convert one of the largest national conference centres into a field hospital, starting with 500 beds with a potential of 4000, is quite frankly incredible."
The new National Health Service hospital will only care for people with COVID-19, and patients will only be assigned there after their local London hospital has reached capacity.
Charles, who earlier this week emerged from self-isolation after testing positive for COVID-19, said he was one of "the lucky ones" who only had mild symptoms, but "for some it will be a much harder journey".
He expressed his hope that the hospital is needed "for as short a time and for as few people as possible".
The latest UK figures showed that the number of people to have died in Britain increased in a day by 569 to 2921.
Australian Associated Press