There is no God but Allah, the God of Prophet Adam, Prophet David, Prophet Moses, Prophet abraham, Prophet Jesus and of Prophet Muhammad and many other who came before Prophet Muhammad. The prophet hood ended in Mecca, where the religion of Allah the creator of Universe, completed... and the mission of all Prophets was completed. Thereafter, will come no more Prophets... only the Holy Jesus will return once to earth, to claim his death... and thereto, guide people to the path of Allah, as Jesus was taken to heaven before he could be killed.... and it is said in Holy Quran that all Living beings will die.... and so will he return.
Mecca is the holy city of Muslims, for there is the center of Islam, the Holy Kaaba. The visible building of today was founded by Abraham, with his son Ismail....where his foot prints are still preserved. It was the place where Abraham left his wife an son from the order of Allah, and there started the city of Mecca... and the holy water of Zamzam.
http://en.wikipedia.org/wiki/Zamzam_Well
It is the same place where Adam and Eve were forgiven for their sin in Heaven, at the mountain peaks of SAFA and MARWA, the same peeks where the wife if Abraham ran 7 times looking for water. It is the same place where the black stone was dropped from the sky to mark to Adam and Eve that they were forgiven.
http://en.wikipedia.org/wiki/Black_Stone