A cannabis plant located on a Cornish high street above a former bank had narcotic plants worth more than half a million pounds.
Three Albanians have been jailed for their roles in the potentially hugely profitable enterprise which operated on the old Natwest Road in Bodmin's Fore Street.
Engjell Osmanaj, 29, Anjelos Selamaj, 22, and Alban Topi, 29, all appeared at Truro Crown Court for sentencing after pleading guilty to producing cannabis.
The court heard how the three Albanians acted in collaboration because of fear of what would happen to their families back home, with Topi even considered a victim of modern slavery.
Following the case, Nicholas Lewin described how in Bodmin in January this year a police warrant was executed in Fore Street at the large four-storey building. Police came across reinforced doors that were locked from the inside.
When they eventually gained access, the defendants were found hiding and trying to escape.
Lewin described the building as a health and safety hazard and officers found Osmanaj's phones and car keys.
In the car, items related to plant growth were found.
Lewin said: "Inside the property, police found a large cannabis farm with the potential to produce cannabis on an industrial scale."
More than 850 plants worth £731,000 were found, British media reported.
The three young men said that they worked to support their families, in difficult economic conditions in Albania.
Lewin said that Topi and Selemaj were gardeners, while Osmanaj had a more advanced role.
Sentencing the defendants, Judge Robert Linford said: “You all entered the country illegally and engaged in serious crimes. All three of you were found at the property on Fore Street.”
"The property had been converted into a cannabis farm. The building included reinforced steel doors, diverted power supplies and was the site of a commercial cannabis growing operation.”
Osmanaj was imprisoned for 40 months, Selamaj 20 months and Topi 16 months.