Court cases are expected to resume at the Old Bailey after an electrical fire inside the high-security building in the City of London.
About 1,500 people were evacuated from the Central Criminal Court and surrounding buildings on Wednesday morning, disrupting dozens of cases.
Smoke spewed from the building and courts were plunged into darkness after the fire in an electrical substation.
London Fire Brigade (LFB) said the cause of the fire was "accidental".
It was not being treated as suspicious, it added.
Two people had to be rescued from lifts during the incident.
Four fire engines and 25 firefighters were called as crowds of barristers in black gowns and wigs gathered at the front of the building.
Defendants were seen being escorted by police out of a side exit and into waiting security vans to be returned to prison remand.
Among the cases affected were the ongoing trial of Constance Marten and Mark Gordon, who are accused of the manslaughter of their baby daughter, and the inquest into the deaths of the victims of the Reading terror attack.
On Friday, Judge Mark Lucraft KC, the Recorder of London, said the building would reopen at noon on Monday following emergency works to restore power after the fire.
He said various health and safety checks were needed before normal business could resume.
The Old Bailey is the world's most famous criminal court and has high levels of security as it hears major criminal cases, including murder and terrorism trials.
In the past, it has been identified as a high-value terror target and was badly damaged in an IRA car bomb attack in 1973.