Police have issued photos showing the aftermath of the £60m raid on a Hatton Garden jewellery vault.
Detectives say the gang drilled a hole 50cm deep, 25cm high, 45cm wide and 89cm from the floor, through a concrete wall before ripping open 72 secure boxes in the vault.
Met detectives say they believe between four and six people entered the building at 9.20pm on 2 April and stayed until 8.05am the following morning. They returned on 4 April at 10.17pm, staying until 6.30am the next day.
DS Craig Turner, head of the Flying Squad, said: "The hours of forensic work and inquiries have been vital in order to ensure we are able to exploit all investigative opportunities to their fullest extent and assist us in identifying those individuals responsible.
“Those safety deposit boxes not opened by the thieves during the burglary have been left secured as they were found throughout the examination. HGSD are in the process of making contact with owners to arrange collection."
No arrests have been made and police are appealing for anyone who may have seen anything, or with information, to contact them. An appeal will be broadcast on Crimewatch on BBC One tomorrow (Thursday).