About Istanbul, Hagia Sophia

Hagia Sophia was built at the command of Emperor Justinian in the years 532 to 537. It was first constructed as a church, then became a mosque and is now a museum.  It has the fourth biggest dome in the world, towering at 56m, it is the largest in Turkey and was the largest in the world until the construction of the Seville Cathedral in 1520. The famous Hagia Sofia is situated in the city centre and many other attractions are within walking distance including Sultan Ahmed Mosque, which sits on the opposite side of the square. The Basilica Cistern and Grand Bazaar are also nearby. 

HISTORY
It was designed jointly by two architects, Isidore of Miletus and Anthemius of Tralles.  Hagia Sofia was originally constructed as a church in the Constantinople era, until it was conquered by the Ottoman Turks in 1453.  It is thought that the church was re-built three times.  Nothing remains of the first church and only several marble blocks from the second church can be found in the garden.  When the Ottoman Turks conquered Constantinople, Sultan Mehmed II ordered that the church be turned into a mosque, with many of the sacred artifacts being removed and mosaics being plastered over.  Many Islamic features were added, including the four minarets that can be seen now.  Hagia Sofia continued to serve as a mosque until 1935, when it was converted into a museum by the Republic of Turkey, the carpets were removed, revealing the marble floor decorations for the first time in centuries.  Also much of the plastering covering the mosaics was removed by restorers.

DOME
The dome of Hagia Sofia is of particular interest to many historians.  The dome was built using a technique that had never been used before for a structure of this type.  The structure works to enable the dome to transition into the same square shape as the piers below it.  Not only is this aesthetically pleasing, but it also restrains the lateral forces of the dome and allows the equal distribution of the weight to flow downwards.

The anomalies in the design of Hagia Sophia show how this structure is one of the most advanced and ambitious monuments of late antiquity.

MOSAICS
The original churches were highly decorated with mosaics, throughout the centuries.  The various mosaics depicted religious themes, such as; Virgin Mary, Jesus, various Saints and Emperors or Empresses. 

When the Ottoman Turks converted the church to a mosque in 1453, the mosaics were covered, as there was a ban in place on representational imagery.  All the mosaics were not covered at once; it was a gradual process, with some imagery still visible as late as the 17th century.

Between the years of 1847 and 1849, the building was restored by brothers Gaspare and Giuseppe Fossati.  The brothers also documented any mosaics they found, however they did not restore most of them, just took detailed descriptions of the images and painted over them.  It was part of their job to cover, previously uncovered mosaics.  Currently there are only four images and two of them are restorations in paint created by the Fossatis to replace two images of which they could find no surviving remains.  The Fossati records are the primary source for a number of mosaic images now believed to have been completely or partially destroyed in an earthquake in 1894.

MINARETS
There are four minarets at the Hagia Sofia, one was built from red brick, whilst the other three were built from white marble.  The minarets vary in dimensions, to counterweight the main structures mass and distribute the weight.  This action by Mimar Sinar was one of the first displays of geotechnical engineering in history.