this is the centre of the muslim world, the 'qibla' (direction of prayer). as mentioned in an earlier post, allah's throne in heaven is directly above it.
the 'tawaaf' (circling of the kaaba 7 times) has not stopped (except for the 5 compulsory daily prayers) for more than 1400 years and will not stop until the day of judgment. it is said that as many as 70,000 angels in heaven do tawaaf around allah's throne and the same angel doesn't do it twice.
although some say the spot has been sacred in existence since the time of prophet adam (peace & blessings be upon him) the holy kaaba was first properly constructed by prophet ibrahim, or abraham with his son ishmael (peace & blessings be upon them) after allah instructed ibrahim to build him a house. he stood upon a stone during its construction. the stone, complete with his footprints, is still in existence. it is housed in the small, gold structure to the extreme right of the picture. this is known as 'maqaam-e-ibrahim'.
the cornerstone of the kaaba in the picture above is the 'hajar-e-aswad' ('the black stone'). it's not visible in the picture. kissing the stone is said to absolve a person of their sins.
i advise people that want to read more on the 'hajar-e-aswad' and other features of the holy kaaba to research into the history of the kaaba alongside the history of makkah, as it is too vast to summarise here. the entire city of makkah was built around this sacred structure.
