Muslims began the annual pilgrimage of hajj Tuesday, marking the start of a centuries-old, six-day tradition that has grown into one of the largest gatherings in the world. Nearly 2 million Muslims pilgrims from around the world were expected to take the journey this year. Here are two different options through which you can watch hajj 2015 live.

Courtesy of Saudi Quran TV Live:

Courtesy of Mecca TV Live:

The Saudi-owned news site Al Arabiya also has a live blog for hajj coverage that you can track here.

Several disasters preceded this year's hajj. Earlier this month, more than 100 people were killed and nearly 400 injured when a construction crane, buffeted by strong winds, collapsed at the Grand Mosque in Mecca. A fire in a hotel in Mecca Monday forced roughly 1,500 people to evacuate, with four people from Yemen mildly injured.

Other concerns include the risk of the MERS coronavirus, thought to have originated with camels in Saudi Arabia, and the war in neighboring Yemen, in which Saudi Arabia is involved. The potential for attacks by supporters of the Islamic State group is also on the government's radar. Some 100,000 police have been deployed at various sites for hajj, Agence France-Presse reported, and security forces were working "to prevent terrorist groups from exploiting hajj season to carry out acts of sabotage," Gen. Mansur al-Turki, a spokesman for the Saudi interior ministry, said.

Hajj is one of the five pillars of Islam. Every able-bodied Muslim, male or female, who can afford the cost of the trip must make the journey at least once in his or her life. Hajj rites include circling the Kaaba, traveling between the mountains of Safa and Marwah, praying on the plains of Arafah and casting stones at pillars that represent the devil.

The end of hajj is marked by the holiday of Eid al-Adha (not to be confused with Eid al-Fitr), in which an animal is sacrificed, a feast is held and people pray and exchange gifts.