German Chancellor Angela Merkel is inaugurating a memorial to thousands of victims of the Holocaust who were ethnic Roma.

Ms. Merkel opens the memorial Wednesday in Berlin, the German capital. The circular pool is located across the street from the German parliament building.

The Nazis deemed the Roma, like the Jews, to be genetically inferior. It is unclear how many Roma were rounded up and killed in the death camps during World War Two, but estimates reach as high as half a million.

This is the third Holocaust memorial in Berlin. There are also memorials to Jews, who made up the vast majority of victims of the death camps, and to those who were killed because they were homosexual.