Three men and a teenage boy have admitted their parts in a burglary at Cambridge's Fitzwilliam Museum earlier this year.
The raid saw millions of pounds worth of ancient Chinese artefacts stolen.
The 15-year-old boy from London pleaded guilty to burglary. Robert Smith, 24, of Hockenden Lane, Kent, Steven Coughlan, 26, of Eleanor Street, London, and a 29-year-old man from London who cannot be named for legal reasons, all pleaded guilty to conspiracy to burgle.
Det Chief Insp Jim McCrorie said: “Today’s guilty pleas follow a large scale police operation and a lot of hard work to ensure those involved in this burglary were caught and convicted."
He said the items - believed to be worth millions of pounds - have yet to be recovered.
“Sadly the items, which are of huge cultural significance, have still not been traced but we remain committed to pursuing new lines of enquiry that could lead to us recovering them."
All four will be sentenced on September 28 at Cambridge Crown Court.
A third person has been arrested in connection with a burglary at the Fitzwilliam Museum in Cambridge.
Police arrested the 31-year-old man from London on suspicion of money laundering. He is in custody at Thorpe Wood Police Station in the capital.
18 items of Chinese art, thought to be worth about £10 million, were stolen during the raid last month.
A 28-year-old man and a teenager have already been charged with the thefts.