A report from Austrian authorities said 600-700 children and youths were kept at "Pavilion 15" under a "comprehensive system of violence" between the end of World War II and the early 1980s.
The report, based on interviews with former patients and staff, said that an "inadequate employment and ideological break with the Nazi period contributed to these inhumane conditions".
Staff, most of whom were inadequately qualified, made "heavy" use of drugs to sedate the children and put them in caged beds and straightjackets.
And at least 70 died at the facility, now closed, around 80 percent of them from lung infections brought on by the harsh treatment and undernourishment, the report said.
"Conditions like this for the treatment of handicapped people... were a long away from professional standards of practice at the time," said Hemma Mayrhofer, one of the report's authors.
The site in the Austrian capital was part of the Am Spiegelgrund clinic where the Nazis murdered almost 800 children, subjecting them to pseudo-scientific experiments or gassing them.
Their remains were used for years after the war for scientific purposes.
Shockingly, the new report said that after the war, the brains of children who died there were given to Heinrich Gross, a senior Nazi doctor who conducted some of those deadly experiments.
Gross (1915-2005), who went on trial but was never convicted and enjoyed a flourishing career after the war, was therefore able to continue research he had begun before 1945, the report said.