Bismillah
salam Steve
Thank you for raising this question and let me help you clear out this confusion.
Actually, we dont worship Mecca.
Mecca is a city that was lent sanctity by Allah, through this sanctity, everything is secured. I mean birds, animals, ..etc. We are not allowed to hunt or kill within the borders of the sanctity domain.
What is in Mecca? Mecca contains Ka`aba, which is the black box you are referring to. No we dont worship the black box, we worship the Lord of the black box Allah.
The black box is called Ka`ba.
What is Ka`ba?
Here is a good thread on it:
http://islamsms.com/bb/index.php?showtopic=3636&hl=
But to be brief:
1. It is where we face to perform prayer, we circle around it as part of Haj and Umra rituals. No not to worship it, but to fulfil Allah's Command to do so. Thus, you can simply say, circling around Ka`ba = prayer. A worhip but to Allah not to the black box.
2. It was built by the angles, demolished and reconstructed by Adam when he came down to earth.
3. Ibraheem and Ishmael - prayer and peace be upon both of them - re built it when it was demolished by a command of Allah.
4. It is where Ibraheem prayer and peace be upon him left his only son then (Ishmaeel) and his wife Hajar as per a command from Allah.
Insh aAllah this reply is satsifactory, if not let me know :)