Officially Hajj 2025 Begins: 2 Million Muslims Gather in Mecca Amid Scorching Heat and Stricter Regulations. Mecca, Saudi Arabia – Hajj 2025 began on Wednesday, June 4, drawing over 2 million Muslims from across 180 countries to the holiest city in Islam. Spanning five days until Sunday, June 8, the pilgrimage involves a deeply spiritual journey filled with traditional Islamic rituals, many of which date back more than 1,400 years.