For centuries, Istanbul was not only the capital of the Ottoman Empire, but also its spiritual centre. Hundreds of tekkes (Sufi monasteries) on the Bosporus served as spiritual schools and places of assembly

The visiting of Sufi shrines (ziyaret in Turkish) is an important devotional practice of popular Islam. For centuries, the holy tombs have attracted believers from all social strata who come to offer prayers, whether it be women hoping to conceive, businessmen hoping for better business, or statesmen faced with important decisions

The tombs of the Istanbul shaykhs, Sufi masters of bygone centuries, are visited by city residents and tourists to this day. One of the most important shrines located on the European side of the city is that of Yahya Efendi (1494-1569), a contemporary of Sultan Suleiman the Magnificent

After Yahya Efendi received permission from his master to teach, he settled down in a garden in the district of Besiktas. This is where he pursued a spiritual life and received guests seeking his blessing. Today, many visit the tomb of Yahya Efendi, not least due to its stunning view of the Bosphorus

) The turban of a saint is placed on his sarcophagus, as shown here at the tomb of Yahya Efendi. The turban serves as a symbol of a master's spiritual rank and they differ in colour and form among the various Sufi orders

Typically, a Sufi tomb is attached to a mosque, so that the visitors can also perform ritual prayers. Many of the shrines have been elaborately restored in recent years

The shrine of Mustafa Devati, a Sufi master from the 16th century, is located on a popular shopping street in the Asian district of Uskudar. Many visit the tomb while shopping or on the way to work

The district of Uskudar is well known for its particularly high concentration of shrines and mosques. Many neighbourhoods and streets are named after illustrious Sufi masters or Dervish monasteries

The tomb of Aziz Mahmud Hudayi (1541-1628), located in the centre of Uskudar. Hudayi, founder of the Jelveti order, is also known as a poet of mystical poetry written in the Ottoman language. His tomb complex includes a Koran school and a library

Among the rituals practiced by visitors to the tomb of Aziz Mahmud Hudayi is the circling of his sarcophagus. Queues of visitors often form on weekends and holidays

The tombs of relatives, students and successors, as well as generations of shrine custodians are frequently found next to that of a Sufi master. They are also accorded due respect from visitors to the shrine

Despite the official ban on Sufi brotherhoods imposed by Mustafa Kemal Atatürk, there are still active Sufi communities in Istanbul today. However, they do not draw nearly as many people as do the tombs of the great Sufi masters of the city