I have seen loads of pictures of Mecca with the black tent in the middle but don't know what is in it.
I have heard that devout muslims will never tell what it is as it is supposed to be a religious relic of such importance that whoever sees it will forever be a believer.
There is nothing secretive about Makkah. The 'black tent' is Ka'ba - the house of God.
It is made up of bricks cut from a mountain in Makkah (don't remember it's name now).
I don't know what is inside Ka'ba ( i personally think it's empty), only important people like presidents get to have a look inside.