St. Peter's

The rise and spread of Christianity is simply without parallel.  There is no record more striking or more pervasive.  While Islam rose to power faster (in one century, compared with Christianity’s three), Western cultural influence, largely fashioned on Christian moulds, is now planet-wide. Where Jewish thought informs Western culture, Christianity largely is Western culture. 

Early on, Christianity did not have or need any church of its own for three hundred years.  A simple table setting for the shared meal sufficed and there was no specified location.  Early church fathers state quite plainly, “We have no temples and no altars.”

But all that changed when Constantine embraced Christianity and won the fateful battle for emperor in 312 A.D.  Its acceptance and growth increased the need for a distinctly Christian house of worship.  "Dining room worship" hardly suited the imperial religion.  And Roman temples could not simply be adopted since they were former pagan god abodes.

Constantine's solution was the basilica, the building in which Roman judicial, commercial, and governmental activities took place.  His one modification to the "long house" form was to add a crossing transept.  Not only did this render the form into a Christian cross it also clearly marked the most important part: the "crossing" and traditional location for Christian altars. 

The first and most important Christian locus was Saint Peter's Basilica. Located in the northwestern extremity of Rome, on the right bank of the Tiber, it sits atop Vatican Hill, an ancient cemetery venerated well before Christianity's rise.

In fact there were two Saint Peter's basilicas built about 1300 years apart. Constantine erected the first c. 330 A.D. and for 1100 years it was the predominant church in all Christendom, influencing design in all parts of Western Europe. 

But by the end of the fifteenth century, Old Saint Peter's was in a bad state of disrepair.  Restoration began in 1506 and continued off and on for some 120 years, through ten architects and a surprising twenty-nine popes.  When completed, it was the largest and most imposing church in the world—continuing so until 1989.  It approaches the Great Pyramid of Egypt in height, and encompasses two and half blocks on the ground.  It remains the heart of the Roman Catholic Christendom today.