The hajj, Islam's annual pilgrimage to Mecca, begins

On Friday, around 2 million Islamic pilgrims are expected in Mecca, a holy city in Saudi Arabia, for the start of the annual hajj pilgrimage. Over five days, the faithful follow a path that is said to have been taken by the Islamic Prophet Muhammad around 1,400 years ago. Muslims always try to pray while facing toward the Kaaba — the square shrine seen here — wherever they are in the world.

On Friday, thousands of pilgrims circled the Kaaba counterclockwise seven times. It is Islam's holiest shrine. Pilgrims also tilt their hearts toward the cube-shaped structure as part of the ritual.

The hajj is one of the most diverse gatherings in the world. Several hundred thousands of the more than 2 million pilgrims are from Saudi Arabia. To avoid any risk to safety, Saudi authorities have urged pilgrims not to discuss politics or divisive issues and to focus on worship.

Most making the hajj will spend Friday night at this tent city in Mina, which can house 2.6 million in total. On Saturday, they will leave for Mount Arafat, around 20 kilometers (12.5 miles) east of Mecca. Wealthier hajjis stay in lavish hotels overlooking the Kaaba. But most people stay in simple accommodations; some even sleep on the ground.

For Muslims around the world, the hajj is meant to be a unifying event and pilgrims shed displays of wealth and materialism. Male pilgrims wear simple white clothes. Women go without makeup, nail polish and perfume. The hajj is seen as an opportunity to strengthen faith and absolve sins. All hajjis, regardless of their backgrounds, perform the same rituals.

As one of the five pillars of Islam, all Muslims are expected to make the hajj once in their lifetime, if they have the physical and financial means. Last year, 2.4 million people took part in the hajj, and a similar turnout is expected for 2019. This year, Saudi King Salman invited 200 survivors and relatives of the mosque attacks in Christchurch, New Zealand, that killed 51 people.