There are two mosques bearing the same name - Sokollu Mehmed Pasha - in Istanbul. This text is devoted to the building located in Kadırga neighbourhood of Fatih District. The second mosque is located in Beyoğlu, on the other shore of the Golden Horn. Who was the person whose merits required not one but two mosques erected in his name in the city that was once the capital of the vast Ottoman Empire? Was he a member of the ruling family? How did he get to the very top of the ruling elite of the empire? His story started at the beginning of the 16th century, from very humble origins deep in the Balkans, in Bosnia, then controlled by the Turks.

The route of the future Grand Vizier - Sokollu Mehmed Pasha - from the village in the Balkans led through a special recruitment system introduced in the Ottoman Empire. It was called devşirme, meaning gathering or collecting in Turkish. However, the term "tribute in blood" probably better reflected the feelings of parents whose sons were "collected" into the Janissaries. The system of devşirme did not rely on the prisoners of war, but it functioned as a taxation system imposed on Christian subjects of Ottoman sultans. Initially, devşirme was limited to the Balkan provinces of the empire, but in time it was also introduced in Anatolia.

The dualism of devşirme perception is something that needs to be remembered when thinking about the fates of the draftees. The astounding careers of such eminent personalities as the most distinguished Ottoman architect Mimar Sinan or Sokollu Mehmed Pasha gave many scholars the excuse to criticise the historians who attacked devşirme as a barbaric act of forcibly taking children from their Christian families to die in the service of sultans. Despite the brilliant careers of the selected few, their momentous achievements do not change the fact that devşirme was perceived as one of the most gruesome aspects of the Turkish oppression, as reflected in Balkan folklore and literature. The children were taken away from their ethnic, religious, and cultural environment, brought to the Ottoman court and forcibly converted to Islam. As Çandarlı Halil Pasha the Elder, the first Grand Vizier of Sultan Murad I's reign, put it: "The conquered are slaves of the conquerors, to whom their goods, their women, and their children belong as lawful possession".

On the other hand, devşirme really offered tremendous perspectives for the talented children of poor Balkanian peasants and was the gateway to a life spent in more comfort that their home villages could offer. Although the draftees of devşirme were technically slaves, they were of great importance to the Sultan because they owed him their absolute loyalty. It resulted from the long process of their education that changed them into highly trained professionals, serving four imperial institutions: the Palace, the Scribes, the Religious, and the Military. The brightest of the students of the Palace School could even aspire to the highest office available to Ottoman subjects, that of the Grand Vizier. The members of this elite often married the princesses of the Ottoman dynasty, accumulated great wealth, and bequeathed it to their heirs.

Sokollu Mehmed Pasha who rose to the most prestigious offices in the Ottoman Empire was also the devşirme recruit. He was born in Ottoman Bosnia into an Orthodox Christian family. Like other boys recruited through the devşirme system, he was forcefully converted to Islam, raised, and educated. He rose through the ranks of the Ottoman administrative system, consecutively holding the positions of the commander of the imperial guard, High Admiral of the Fleet, Governor-General of Rumelia, the Third Vizier, the Second Vizier, and the Grand Vizier. Moreover, the promotion of a former Christian boy into the highest rank available for people not born in the Ottoman family was not an exception. Quite the opposite, as out of 39 grand viziers who governed from 1453 to 1591, only one was Turkish, and at least 15 got to the services of the sultans through devşirme.

Sokollu Mehmed Pasha was also bound to the ruling Ottoman dynasty by marriage. He married Ismihan Sultan, the daughter of Sultan Selim II and his beloved consort Nurbanu, and the granddaughter of Suleyman the Magnificent and his favourite consort Hürrem Sultan.

Sokollu's career lasted from 1543 to 1579 under the rule of three sultans: Suleyman the Magnificent, Selim II, and Murad II, reflecting the career of architect Mimar Sinan. For the last 14 years, Sokollu was de facto ruler of the Ottoman Empire. His career was abruptly finished when he was assassinated in very mysterious circumstances. He was buried at the mausoleum built for him by Mimar Sinan.

Amazingly, Sinan's most frequent customer was not Sultan Suleyman who is accredited with 27 buildings of Sinan, but Sokollu Mehmed Pasha. This dignitary ordered 32 structures from the chief architect. Sokollu Mehmed Pasha was a very generous sponsor of numerous buildings in Constantinople and throughout the Ottoman Empire, from the Balkans in the west to the holiest cities of Islam - Mecca and Medina in the east. His best-known contribution to the architecture of his home country - Bosnia - is the bridge in his hometown of Višegrad, erected by Sinan. However, this is not the place to discuss the history of that magnificent structure that was beautifully described in the novel "The Bridge on the Drina", written by Nobel laureate Ivo Andrić.

Sokollu Mehmed Pasha Mosque Complex was commissioned jointly by the grand vizier Sokollu Mehmed Pasha and his wife Ismihan Sultan, designed by the imperial architect Mimar Sinan. Although Ismihan Sultan and her husband jointly endowed the mosque, only Sokollu Mehmed Pasha is listed on the foundation inscription. According to the same inscription, placed above the north entrance to the courtyard, the mosque was completed in the Islamic year 979 (1571/72 CE). The complex included a mosque, a medrese, a dervish lodge (tekke), latrines, and a reservoir with a street fountain. The inscription also explains that the site where the complex was erected had once housed Saint Anastasia Church that collapsed before the mosque was built.

Sokollu Mehmet Pasa Complex is one of the most refined of Sinan's designs as it was erected in the architecturally challenging location on a steep slope. The site slopes downwards toward the Sea of Marmara, so the northeastern part of the site is the highest, and the southwestern part the lowest. The medrese, the mosque, and the dervish lodge are situated in line along the southwestern side of the enclosure. The main entrances are in northwestern, southwestern, and northeastern walls. They lead onto the medrese courtyards via a series of corridors.

Moreover, the architect had to fit the complex into the existing urban fabric of the thriving Ottoman capital. Sinan used an innovative solution and fronted the mosque with a two-storied courtyard. The lower level was divided into smaller spaces that opened outside and functioned as shops. The rent for those shops was to support the upkeep of the complex. The upper story had an open colonnaded courtyard. In the centre of the courtyard, there is an ablution fountain with twelve columns supporting an onion-shaped dome. The spaces between the columns on three sides of the courtyard were walled off. Thus, they formed sixteen small domed rooms, each equipped with a small window, a fireplace, and a niche to store bedding. These were the rooms that provided accommodation for the students of the religious school, i.e. a madrasah. In the centre of the portico on the northwest side, opposite the mosque portico, there is one larger domed chamber that functioned as the study hall (i.e. dershane) of the medrese.

The fourth side of the courtyard is formed by the mosque portico, higher than the other three porticoes. This portico has seven bays, each covered by a domed cupola and supported by pointed arches. In the middle bay of this portico, there is a grand portal providing access to the prayer hall. This space has dimensions of around 15 by 19 meters. Its plan was designed as a hexagon inscribed in a rectangle and the structure was topped by a dome with four small semi-domes in the corners. The dome has a diameter of 13 metres and it rises almost 23 meters above the floor. The load from the dome is transferred to six colossal piers called the elephant feet.

The mastery of Mimar Sinan is visible in the architectural solutions that greatly improved the acoustics and illumination of the mosque. A total of 98 windows light the prayer hall, and 18 of them pierce the drum of the dome, while the stained glass windows create a colourful ambience. The mosque is beautifully decorated and the attention is immediately drawn to elegant Iznik tiles in the shades of blue, red, and green. They climb high to the pendentives of the dome. They also surround the marble mihrab that is ornamented with polygonal arabesque and muqarnas carvings. The tiles display floral and geometric motifs but also numerous inscriptions written in white thuluth letters on a blue background.

The mimbar and the platform for the muezzin, supported by five columns, are also made of marble. The interior columns were made of polychrome marble. Originally, parts of the mosque had painted decorations. Unfortunately, most of the paintwork has been removed during the renovations. Some original fragments have been preserved under the ceilings of the side galleries, above the vestibule of the north entrance, and on the brackets supporting the balcony above the entrance.

The dervish lodge is located on the opposite side of the mosque and it has its own courtyard. The tekke is a single domed structure about 12 by 7 meters, standing in the centre of the yard and surrounded by cells on its west and east sides. The eastern row is two-stories high while the western one has one level only.

One of the fascinating features of Sokollu Mehmed Pasha Mosque is the fact that it has four pieces of Hacer'ul Esved, the Black Rock from Kaaba, built into its walls. What makes these tiny pieces of black rock so special? It is said that they are fragments of the Black Stone - a rock set into the eastern corner of the Kaaba, the ancient building in the centre of the Grand Mosque in Mecca, Saudi Arabia. This object is revered by Muslims as a relic which, according to Islamic tradition, dates back to the time of Adam and Eve.

This tradition explains that it fell from heaven as a guide for Adam and Eve to build an altar and was much later set intact into the Kaaba's wall by prophet Muhammad. Therefore some people believe that it is a stony meteorite. Other theories claim that it may be a basalt stone, an agate, or a piece of natural glass. However, as the Black Stone has never been analysed with modern scientific techniques, its origins remain the subject of wild speculations only.

Over the centuries, the Black Stone suffered many desecrations and damage. Numerous stories are told relating how it was smashed to pieces and then glued back together, stolen for ransom, hit again, and even smeared with excrement. Exactly how some of the fragments made their way to Istanbul remains a mystery, and even their authenticity remains uncertain.

One piece of the Black Rock from Sokollu Mosque is located above the main doors where it is set in a wavy golden outline. The others are in the mihrab, also with a golden outline, in the mimbar's platform, and on the arch near the stairs to mimbar. According to the accounts of numerous travellers, these precious fragments from Mecca are the reason why taking photographs of the interior of the mosque is frowned upon. The visitors are encouraged to buy a set of photos instead.

The fact that there are as many as four such fragments in Sokollu Mehmed Pasha Mosque makes this building extraordinary. There are two other locations in Istanbul alone that boast such fragments. One piece of the (supposed) Black Stone can be found in the famous Sultan Ahmed Mosque, popularly known as the Blue Mosque. It decorates the alcove of mihrab where several dark stones are located but this special one is set in the golden frame. Another piece of Black Stone is set into the façade of the mausoleum of Sultan Suleyman the Magnificent, on the top of the arch located directly above the entry.

Finally, one fragment of the Black Stone can be seen in the old capital of the Ottoman Empire - Edirne (Adrianople). There is a piece of it placed in the Old Mosque (Eski Cami), distinguishing this building from other mosques of the city. This small black stone is known as Rukn-u Yemani and can be found on the wall of the window near the mimbar. Its location - called the Valley of Heaven - is believed to make the wishes come true and the prayers to be heard.

However, the fact that there are four pieces of the Black Stone inside Sokollu Mehmed Pasha Mosque signifies that the person that sponsored the complex was of the highest importance. Even Sultan Suleyman the Magnificent merited only one such piece. In this context, it is not significant whether these small stones are really from Mecca and if they are from Earth or outer space. What really matters is the powerful position of Sokollu Mehmet, the boy from the Balkans, who became the most powerful person in the Ottoman Empire.