The March of the Living is an annual educational program which brings students from around the world to Poland, where they explore the remnants of the Holocaust. On Holocaust Memorial Day observed in the Jewish calendar (Yom HaShoah), thousands of participants march silently from Auschwitz to Birkenau, the largest Nazi concentration camp complex built during World War II. The program was established in 1988 and takes place annually for two weeks around April and May, immediately following Passover. Marchers have come from over 50 countries, as diverse as United States, Canada, Australia, New Zealand, China, Estonia, Panama, Mexico, Argentina, Brazil, Hungary, and Turkey. The Israeli founders of the March of the Living were Avraham Hirschson and Dr. Shmuel Rosenman. They were assisted in the early years by Jewish communal leaders and philanthropists from the United States (Alvin Schiff, Gene Greenzweig and Joseph Wilf, the first North American Chair of the March of the Living), and Canada (Walter Hess, Shlomo Shimon, Rabbi Irwin Witty, and Eli Rubenstein).