Over 2 million Muslims will take part in this week’s Hajj pilgrimage to the holy city of Mecca in Saudi Arabia. It’s one of the world’s largest religious gatherings, and is returning to full capacity following years of coronavirus restrictions. The Hajj is one of the five pillars of Islam, and all Muslims are required to undertake it at least once in their lives if they are physically and financially able to do so. For the pilgrims, it is a profound spiritual experience that wipes away sins, brings them closer to God and highlights Muslim unity. For the Saudi royal family, which captured Mecca in the 1920s, organizing the pilgrimage is a major source of pride and legitimacy.