Birmingham Prison has been given its best inspection report.
A new gym and
After an unannounced visit in May, the Chief Inspector of Prisons, Anne Owers, said it was now a place where "positive attitudes are firmly embedded".
Governor Mike Shann was singled out for praise but Friday's report warned that some areas such as detox facilities and overcrowding needed improvement.
The Prison, the second biggest in England, has invested in a new medical wing and a purpose built gym.
Drug treatment unit
Governor Mike Shann is widely credited with improving the prison's conditions and relations between prison staff and inmates.
He said: "It is about that decency - treating prisoners with decency and I think that's what we have majored on.
"That is what we've always plugged as the main agenda, everything else springs from that."
The prison's capacity has increased from 930 to 1,400 and the report says a voluntary drug treatment unit is needed.
Detox facilities were said to be inadequate, as is work with foreign national prisoners, and overcrowding at the jail is still an issue.