The Kaaba, in Mecca, is one of the most sacred sites in Islam.
The Kaaba is a granite cube-shaped structure, housed within the Masjid al-Harām (the most sacred mosque in Islam) in the centre of the city.
Pilgrims taking part in the Hajj, one of the Five Pillars of Islam, are required to walk around the Kaaba seven times in a counter-clockwise direction, during several parts of the Hajj. Around six million pilgrims gather for the Hajj to perform this circumambulation.
The Kaaba contains the Black Stone, said to have been put there by the prophet Muhammad in 605AD. According to tradition, the stone fell from heaven, to show Adam and Eve where they should build an altar. More recent scientific theories as to the origin of the stone include that it fell as a meteorite. Today the stone is in several fragments, which have been cemented into a silver frame attached to the side of the Kaaba.
During the Hajj, which is performed once a year, and the Umrah pilgrimage, which can be performed at any time of the year, pilgrims attempt to kiss the Black Stone. Once they have done so, they are pushed away by a guard. If they cannot reach the stone, they point to it each time they circle it.
The Kaaba stands on a marble base, and its corners point towards north, east, south and west respectively. Its east and west corners are aligned with the sunrise of the summer solstice and sunset of the winter solstice.
Muslims throughout the world face towards the Kaaba while praying.