Police swooped at addresses in Salisbury Road in the Cape Hill area and discovered plants worth more than £700,000 in street value.
Two people were arrested at the scene and are being questioned in connection with the illegal production of cannabis.
Rows of plants in various stages of growth covered floors on ground and upper floors. Between the two terraced houses, 700 plants were recovered.
Officers forced their way into the properties and found sophisticated cannabis farm set-ups inside.
The letterboxes had been sealed to prevent the escape of the telltale pungent aroma of the Class 2 drug.
Inside the addresses, wooden posts had been erected to accommodate electricity points and wiring to power the whole operation. Strong overhead lamps hung from the ceilings and fans had been set up to regulate the heating
Plants filled almost every room, from seedlings to plants that…