The Basilica of Hagia Sophia was constructed by Roman Emperor Justinian in 537 AD. This was the largest church in the Christian world for a thousand years. Its immense dome rises nearly 200 feet above the ground and its diameter spans more than 100 feet. The mosaics covering the walls are among the most important works of art that have survived to this day of the Byzantine era.

Large round buildings had been successfully covered by domes before, but Hagia Sophia had a rectangular floor plan, and covering a large rectangular structure by a huge central dome was being tried for the first time in history. The dome collapsed and was repaired many times.

The Ottomans converted the basilica to a mosque in the 15th century after the conquest of Istanbul. Recognizing its historic and universal importance, the Turkish Government turned it into a museum in 1935

Sultanahmet Mosque is the most famous monument in both the Turkish and the Islamic worlds. It was built in the classic Turkish architectural style between 1609-1616 by the architect Mehmet. The building is more familiarly known as the Blue Mosque because of its magnificent interior paneling of more than 20,000 blue and white Iznik tiles.

The inside is a single immense space into which the light pours from 260 windows. The dome 141 feet high, is supported by four enormous circular pillars 16 feet in diameter and are known as elephant feet. As it is located across Hagia Sophia, the mosque was designed to be as large and as magnificent as this Byzantine structure.