Her Majesty the Queen met staff at The Royal London Hospital during an e-visit to open a unit in her honour.
She formally opened The Queen Elizabeth Unit at the Whitechapel facility in a ceremony staff and patients joined from ward 15C.
The Queen, who appeared virtually from Windsor Castle, was introduced to staff who delivered nursing, medical and pastoral care during the Covid pandemic.
The 155 critical care bed unit took its first patients in December 2020.
Barts Health NHS Trust, which runs the hospital, said this allowed the hospital to triple its critical care capacity.
In a video posted to the trust's YouTube channel, Royal London chief executive Jackie Sullivan told the Queen how the unit had been built in five weeks when it would normally take five months.
Her Majesty replied: "It's amazing isn't it what can be done when needs be."
A plaque was unveiled on the Queen's behalf by Sir Kenneth Olisa, lord-lieutenant of Greater London.
Ms Sullivan said: “It was an honour to host Her Majesty the Queen. It has been a challenging two years for our hospital and the attendance of Her Majesty shows how much the care we provide to our patients is valued.”
Among those who met the Queen was Mireia Lopez Rey Ferrer, a senior sister who cared for patients during the first and second wave of the pandemic.
She said: “I never thought I would have the opportunity to do something like this – it was inspiring to hear her talk and ask questions about our experiences.”
The peak number of patients at Royal London who were severely ill with Covid was 156, the trust said.
One patient treated for Covid on the unit was Asef Hussain, who met the Queen with his wife Shamima.
He told the Queen: "I saw the brilliant work the nurses, the doctors, the whole team here were doing.
"They supported me and my family in a fantastic way."
The Queen asked him if he was now feeling better and Asef said: "I'm getting there. I'm recovering, I'm much better.
"I recently left the wheelchair so I'm walking about now."
On meeting the Queen, Asef said: “It was an honour and a privilege. She was a very warm lady who was interested in my story - it was lovely."
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