Why do you think an altar is the centerpiece of so many religions? What is its profound meaning for Catholics?

Duncan G. Stroik, professor of architecture at the university of Notre Dame school of Architecture, wrote: “Symbolically, we should build the altar first and work our from there” and “come to grips with the profound meaning of the altar and allow it to influence our design of the church.”  Why do you think an altar is the centerpiece of so many religions?  What is its profound meaning for Catholics?