A cannabis farm consisting of about 460 plants with a street value of £1.8m has been found by police.
The plants and equipment were found across 13 rooms at a property in Bentley Road, Toxteth, on Thursday.
Four men, including two from Solihull and one from Birmingham, have been held on suspicion of production of cannabis.
Insp Leigh Price, from Merseyside Police, said: "The electricity had been bypassed in a complex way. Thankfully it has now been made safe."