Hagia Sophia (02:12)

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Hagia Sophia was built over 1,500 years ago. During its tenure, it has transformed from a Christian church to an Islamic mosque, to a museum; all while remaining intact during multiple seismic events. In this program, a team will build a scale model of the building and test it using hydraulic platforms. (Credits)

History of Hagia Sophia (03:07)

Built in 537 CE, the Hagia Sophia began as a Christian church, transformed into a Muslim Mosque, and then became a museum. The edifice stands in Istanbul and resides near the North Anatolian Fault. In 1999, an earthquake close to the city killed 17,000 people, but the Hagia Sophia remained standing.

Studying Hagia Sophia's Architecture (02:54)

By creating a model, engineers hope to discover the building's strengths and weaknesses for withstanding another earthquake. Eser Cakti studies the structural integrity. Sensors detect movement in two of the four arches buttressing the dome.

Seismic Shake Table Test (02:26)

Cakti collaborated with Eren Kalafat and Korhan Oral to build a model of the Mustafa Pasha Mosque and test its structural integrity during an earthquake; results showed where weaknesses. The team decides to build a 26:1 scale model of Hagia Sophia to perform a similar experiment.

Who Built Hagia Sophia? (05:48)

After founding Constantinople, the Byzantine Empire grew as the Roman Empire declined. When Justinian ascended, riots broke out across the city; he ordered the army to slaughter the masses. The Byzantine Emperor hired Anthemius of Tralles and Isidorus of Miletus to merge the Basilica and Parthenon into the Hagia Sophia.

Model Building (04:58)

The research team experiences a setback after an arch collapses; Cakti realizes that buttress piers are needed to ensure that the dome does not collapse. By building pendentives, architects transformed the circular dome into a square. Anthemius of Tralles and Isidorus of Miletus complete the Hagia Sophia in six years.

Reconstruction (04:21)

Twenty years after the monument's unveiling, the Hagia Sophia's dome collapses after a catastrophic earthquake; Isidorus the Younger oversaw its rebuilding. When Mehmet conquered Constantinople, he installed minarets, a minbar, and plastered over Christian mosaics to transform it into a mosque.

Hidden Christian Mosaics (04:46)

Hitoshi Takanezawa uses an electromagnetic scanner to detect hidden mosaics. Luciana Notturni and Gabrielle Warr demonstrate how artisans created the mosaics incorporating tesserae and gold leaf.

Hagia Sophia's Composition (02:35)

Sonay Sakar removes cement and repairs the bricks; modern bricks weigh more and the mortar is less flexible than traditional methods. By making the structure lighter, the building can sway with the wind and seismic activity.

Semi-Dome Model Failure (02:17)

Cakti and the research team create mortar that mimics period mortar for the semi-dome. As researchers remove the wooden mold, a crack appears; it is too weak for the shake table test.

Searching for Christian Mosaics (05:32)

Takanezawa discovers metal structural support at the uppermost level. Gaspare Fossati restored the mosque in 1847 and documented each Byzantine mosaic before plastering over its images. After studying records, Takenezawa believes there is a large image of Jesus Christ at the top of the gold dome.

Shake Table Test (10:59)

After the research team moves the model, they observe interior cracks, but nothing that compromises structural integrity. When an earthquake occurs overnight, sensors indicate that the model and Hagia Sophia move in similar manners. After simulating large-scale earthquakes every day for a week, the dome collapses.

Credits: Hagia Sophia - Istanbul's Ancient Mystery (01:12)

Credits: Hagia Sophia - Istanbul's Ancient Mystery