text: Scores of architects worked on the church from the 13th to the 17th centuries ( its central bronze doors were added in 1964 ) , but its glory remains the gleaming facade ( its mosaics were a 17th-century addition ) , with its four slender spired pilasters and its rosewindow above the beautifully scrolled porches .
  
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  The church 's central bronze doors were added in 1964 .