"In March 1943 4,000 Jews from Bulgarian-controlled Thrace in Greece were rounded up and sent to their deaths at Treblinka.
A week later another 7,000 Jews from nearby Macedonia in Yugoslavia were shipped to a tobacco company, whose buildings were converted into a concentration camp (pictured).
The Jews were kept there a few weeks, then sent to Treblinka.
Few survived."
They don't yet know the full extent of the horror.