London's Barbican is among 14 new Nightingale Courts across England set to clear backlog of 50,000 cases.
The additional temporary courtrooms, set up in hotels, theatres and conference centres, will help reduce delays and deliver justice for victims, the Government said.
A further court in Croydon will be set up along with sites in Liverpool, Wolverhampton, Chichester, Birmingham and Manchester.
A total of 23 Nightingale Courts are now up and running, but figures from HM Courts and Tribunal Service show a backlog of around 56,000 cases, with some trials being delayed for months and years and victims waiting for justice.
Hearings in crown courts have slowed due to social distancing measures put in place limiting the numbers in court buildings for lawyers, defendants, witnesses and jurors.
The Mayor of London, Sadiq Khan, said: “London has been disproportionately affected by the backlog of cases and we are facing unprecedented pressure on our courts. I’ve asked Ministers for the urgent introduction of a large enough courtroom for multi-defendant cases to be heard whilst also maintaining social distancing measures, and an increase to sitting hours in court.
"The Government is simply overlooking the serious pressures the city is facing by not locating a ‘super courtroom’ here in London. Swift prosecution is crucial to achieving effective and efficient justice, keeping the public safe and ensuring public confidence in the criminal justice system.”
The Lord Chancellor Robert Buckland, added: “We have achieved an immense amount in our battle to keep justice moving during the pandemic – restarting jury trials before anyone else, turbo-charging the rollout of video technology, bringing magistrates’ backlogs down, and opening more courtrooms for jury trials.
“These new courts are the latest step in that effort, and I am determined to minimise delays and ensure justice is served for victims, defendants and the public.”
Caroline Bull, CEO of CCT Venues, London, said: “We are delighted to be supporting the work of HM Courts and Tribunal Service (HMCTS) through the provision of space for two temporary Nightingale courtrooms at our CCT Venues-Barbican location.
“Although the majority of our traditional business is corporate meetings and events, this has been severely curtailed during the pandemic, so supporting this important project has created a win-win situation.”