More than 2,000 cannabis plants - worth more than £600,000 on the street - were discovered in a police raid on an old Royal Mail sorting office in Herefordshire.
Police today said it was the biggest cannabis factory ever discovered in the county.
Two men have been arrested on suspicion of producing the Class B drug.
A total of 2,180 cannabis plants plus growing equipment were seized by the officers, who executed the warrant in Bromyard.
The raid was carried out after passers-by reported a strong smell of cannabis.