Drugs worth more than £2 million were discovered at one of the largest cannabis factories found in Whittlesey on Monday (9 September).
Hundreds of plants, many ready to harvest, were found in a giant warehouse in an industrial estate on Benwick Road, Whittlesey.
It was only uncovered after a member of the public spotted an open door.
Detectives are now trying to track down the culprits behind the operation.
The factory itself was housed in large covered section of the warehouse, built with a timber frame and cardboard and lagging walls and roof.
On Tuesday officers started dismantling the factory, removing buckets of plants and bags of compost, while hunting for evidence.
Detective Sergeant Matt Swash said: “We found in a vast commercial unit, a large factory, with between 800 and 1,000 plants growing at various stages.
“For me, it is the biggest I have seen, and is probably the biggest ever seen in the county.
“We had a report from a member of the public who was concerned there had been a break- in or attempted break -in at the premises.
“When officers attended they went inside to check they discovered the factory.”
DS Swash said the plants were in three different stages of growth, with around 500 ready to harvest and be sold on the street.
He said: “Clearly this is a significant find for Cambridgeshire police. When we are talking in terms of a street value of around £2 million, it is obviously a serious dent in this industry.
“Our priority is to go beyond that, investigate forensically, pursue further lines of inquiry to identify who is behind this set up and who was here seeing to the plants.”
Councillor Ralph Butcher, from Whittlesey Town Council, said he was shocked to hear of the find.
He said: “While you know there is something like this going on all the time somewhere, it is a shock to find it is going on on our own doorstep.
“It is pleasing the police have discovered it and put a stop to it.’’
No arrests have been made and anyone with information should call police on 101 or Crimestoppers, anonymously, on 0800 555 111.