Construction of the Cathedral began on Christmas Day, 1842 with the laying of the cornerstone by King Otto and Queen Amalia.
Workers used marble from 72 demolished churches to build the Cathedral's immense walls. Three architects and 20 years later, it was complete. On May 21, 1862, the completed Cathedral was dedicated to the Annunciation of the Mother of God '(Ευαγγελισμός της Θεοτόκου)' by the King and Queen. The Cathedral is a three aisle, domed basilica that measures 130 feet long, 65 feet wide, and 80 feet high. Inside are the tombs of two saints killed by the Ottoman Turks during the Turkish Occupation: Saint Philothei and Patriarch Gregory V.