Basilica began as a major public building in Rome and became a sepecial category of Greek Orthodox and Christian Architecture. basilica 1541, from L. basilica "building of a court of justice," and, by extension, church built on the plan of one, from Gk. (stoa) basilike "royal (portal)," the portico of the archon basileus, the official who dispensed justice in Athens, from basileus "king" (see basil). In Rome, applied specifically to the seven principal churches founded by Constantine. http://www.etymonline.com/index.php?term=basilica