A large NHS teaching trust is to be placed in special measures after inspectors rated it inadequate.
St George's University Hospitals NHS Foundation Trust in Tooting, south-west London, will enter special measures after Care Quality Commission (CQC) said it was inadequate for safety and on the issue of being well-led.
The trust was also told it requires improvement for being effective and responsive, although it was rated good for caring. A total of 18 NHS trusts in England are now in special measures.
An inspection at St George's in June and July revealed that several of the buildings, including operating theatres, were so poorly maintained they were not fit for purpose.
Other problems included staff not following infection control policies and about half of staff working with children had not completed the required safeguarding training.
Two years ago, the trust was ranked as good.
Professor Sir Mike Richards, the Chief Inspector of Hospitals, said: "I am disappointed that we have found a marked deterioration in the safety and quality of some of the trust's services since we inspected two years ago, as well as in its overall governance and leadership.
"Our inspectors found that several of the trust buildings - including operating theatres - were in a state of disrepair which meant they were not fit for purpose. There were poor fire detection systems and a heightened risk of water contamination, which meant that people were put at risk.
"We also observed that not all staff followed infection control procedures, even when challenged by colleagues.
"Worryingly, we found that areas in which children and young people with mental health conditions were cared for had not been checked for ligature points, and that half of the medical staff working with children and young people had not completed level three safeguarding training, which is a requirement for all staff working with children.
"We took urgent action requiring the trust to address the most immediate of our concerns, and the trust has now introduced a range of supportive measures as a means of stabilising the organisation."
The trust, which operates hospitals at the St George's and Queen Mary's sites, serves around 1.3 million people.
Interim hospital trust chairman Sir David Henshaw said progress had been made but added: "There will be no quick fix to the problems we face.
"Many of these challenges are due to very poor board and senior management decisions in the past and a failure to tackle the big challenges head-on.
"We owe it to our staff and patients to make St George's better again. The CQC's report is a key part of this improvement journey."
The other 17 trusts in special measures for quality of services are Barking, Havering and Redbridge NHS Trust; Barts; Brighton and Sussex; Cambridge University; Colchester University; East Kent; East Sussex; London Ambulance; Medway; North Cumbria; Princess Alexandra Hospital; Sherwood Forest; South East Coast Ambulance; Walsall; West Herts; Worcestershire Acute; and Wye Valley NHS Trust.
Eight more trusts are in financial special measures owing to large deficits and poor management.