Germany has inaugurated a memorial to more than 200,000 people with physical and mental disabilities who were killed by the Nazis after their lives were deemed "worthless."

The memorial in Berlin is close to monuments to the Jewish Holocaust victims and to the Nazis' gay and Gypsy, or Roma, victims.

The 79-foot blue glass pane stands on the site of a villa where the mass murder of patients at hospitals and mental institutes was coordinated starting in 1940. The euthanasia program's methods included using gas chambers.

Sigrid Falkenstein, whose aunt was killed in 1940, said Tuesday it was "a technology of killing tested and carried out for the first time on defenseless, sick and disabled people, a test run for all the Nazis' following programs of mass eradication."