Duomo Central Tympanum Mosaic
A tympanum is a semi-circular wall above an entrance and an archivolt are the ornamental moldings that follow the arch.
Few are more gorgeous than this one that surrounds a mosaic called "Christ enthroned with Mary and John the Baptist."
All three mosaics on the Cathedral of Florence’s façade were designed by Nicoolò Barabino.

Florence's cathedral is the 4th largest in the world, after St. Peter's in Rome, St. Paul's in London and the Duomo in Milan.