Begun in 1143, its arcaded facade varies the patterns of its four tiers of columns sculpted, striped, scrolled, chevroned in pink, green, black, or white marble.
 The colors of the marbles are representing the different eras and battles.
mnli hypothesis:  The colors of the marbles are representing the different eras and battles. premise: Begun in 1143, its arcaded facade varies the patterns of its four tiers of columns sculpted, striped, scrolled, chevroned in pink, green, black, or white marble.