Pilgrims flooded into the Arafat plain from Mecca and Mina before dawn on Monday for the annual Hajj, a visit to the site where the prophet Muhammad gave his farewell sermon on this day in the Islamic calendar 1,378 years ago.drew 3 million visitors this year, the BBC reports, making it the largest yearly gathering of people in the world.

The end of Hajj will mark the beginning of Eid al-Adha, which starts Tuesday. The Eid al-Adha, or the "Festival of Sacrifice," commemorates Abraham's willingness to sacrifice his son, Ismail, on God's command. Cattle, goats and camels are slaughtered the morning of the festival and the meat is shared with the poor.

A Muslim pilgrim prays on a rocky hill called the Mountain of Mercy on the Plain of Arafat near Mecca, Saudi Arabia.

Muslim pilgrims leave an autograph at Mount Arafat.

Muslim pilgrims look at a map as they arrive at the Mina valley east of the Saudi Arabian holy city of Mecca.

Muslim pilgrims perform the walk around the Kaaba (Tawaf) at the Grand Mosque in Mecca. The Kaaba, Islam's holiest site, contains the holy Black Stone which is believed to be the only piece remaining from an altar built by Abraham.

The half moon is seen behind the minaret of the Namira Mosque at Mount Arafat.

Kashmiri women purchase food at an outdoor market ahead of the Eid al-Adha festival in Srinagar.

Pakistani camel sellers drink tea at a sacrificial livestock market ahead of Eid al-Adha in Lahore.

A Lebanese farmer carries a lamb at his farm in the Bekaa Valley as he prepares to sell some of his livestock in preparation for Eid al-Adha.

Decorated cows are seen at a sacrificial livestock market ahead of Eid al-Adha in Lahore.