This incredible live webcam view shows the gathering at Mecca:
Mecca Webcam, Saudi Arabia
Al-Masjid al-Ḥarām (Arabic "The Sacred Mosque") is the largest mosque in the world. Located in the city of Mecca, it surrounds the Kaaba, the place which Muslims worldwide turn towards while offering daily prayers and is Islam's holiest place. The mosque is also known as the Grand Mosque.
The current structure covers an area of 4,008,020 square metres (990.40 acres) including the outdoor and indoor praying spaces and can accommodate up to four million Muslim worshippers during the Hajj period, one of the largest annual gatherings of people in the world. The Haram is the focal point of the hajj and umrah pilgrimages that occur in the month of Dhu al-Hijjah in the Islamic calendar and at any time of the year, respectively. The Hajj pilgrimage is one of the Five Pillars of Islam, required of all able-bodied Muslims who can afford the trip. In recent times, about 3 million Muslims perform the hajj every year.
Some of the rituals performed by pilgrims are symbolic of historical incidents. For example, the episode of Hagar's search for water is emulated by Muslims as they run between the two hills of Safa and Marwah whenever they visit Mecca.