At the Auschwitz-Birkenau Memorial in Poland, a quote on the wall of one

of the cell blocks reads, "Those who do not remember the past are

condemned to repeat it." These words are attributed to George Santayana,

and they help explain why the former death camp is still open for public

viewing 74 years after it was shut down. Historical amnesia was a real

danger after the Holocaust, and with so many other tragedies that have

followed, it's still a threat today.