18th of Safar. Shia Al-Arba‘īn (, "The Forty"), Chehelom (, , "the fortieth [day]") or Qirkhī, Imāmīn Qirkhī ( (), "the fortieth of Imam") is a Shia Muslim religious observance that occurs forty days after the Day of Ashura. It commemorates the martyrdom of Husayn ibn Ali, the grandson of Muhammad, which falls on the 20th or 21st day of the month of Safar. Imam Husayn ibn Ali and 72 companions were killed by Yazid I's army in the Battle of Karbala in 61 AH (680 CE). Arba'een or forty days is also the usual length of mourning after the death of a family member or loved one in many Muslim traditions. Arba'een is one of the largest pilgrimage gatherings on Earth, in which up to 31 million people go to the city of Karbala in Iraq. The second largest holy city in the world, Mashhad, Iran, attracts more than 20 million tourists and pilgrims every year, many of whom come to pay homage to Imam Reza (the eighth Shi'ite Imam). It has been a magnet for travelers since medieval times. Judaism While Solomon's Temple stood, Jerusalem was the centre of the Jewish religious life and the site of the Three Pilgrimage Festivals of Passover, Shavuot and Sukkot, and all adult men who were able were required to visit and offer sacrifices (korbanot) at the Temple. After the destruction of the Temple, the obligation to visit Jerusalem and to make sacrifices no longer applied. The obligation was restored with the rebuilding of the Temple, but following its destruction in 70 CE, the obligation to make a pilgrimage to Jerusalem and offer sacrifices again went into abeyance. The western retaining wall of the Temple Mount, known as the Western Wall or "Wailing" Wall, is the remaining part of Second Jewish Temple in the Old City of Jerusalem is the most sacred and visited site for Jews. Pilgrimage to this area was off-limits to Jews from 1948 to 1967, when East Jerusalem was under Jordanian control. There are numerous lesser Jewish pilgrimage destinations, mainly tombs of tzadikim, throughout Israel and Palestine and all over the world, including: Hebron; Bethlehem; Mount Meron; Netivot; Uman, Ukraine; Silistra, Bulgaria; Damanhur, Egypt; and many others. Many rabbis claim that even today, after the destruction of the Temple, there is a mitzvah to make a pilgrimage on holidays. Sikhism Sikhism does not consider pilgrimage as an act