The Sümbül Efendi Mosque, located in Kocamustafapaşa, was originally the Hosios Andreas Monastery and Church. It was founded by the Empress Theodora as a monastery for girls. After the conquest of Istanbul, the church was found in disappear and in 1489 it was converted to a mosque by Koca Mustafa Paşa. Over time a madrassa, han, soup kitchen, hamam and fountains were added and the area was converted into a mosque complex (kulliye).
The mosque has a central dome built in the Turkish style, which rests on two half domes. The exterior walls were covered by Turkish style masonry. While the interior of the mosque feels Byzantine, the exterior has been entirely redone in Turkish style.
The Ottoman tradition of lighting lamps in the minarets began in this mosque.
Mosque is a place of worship for Muslims. It comes from the Arabic word 'masjid' which literally means "a place for prostration". Mosques are also places where Muslims come together for different purposes such as education, social gatherings, public meetings, exhibitions, lectures etc. Although there is no specific requirement for mosques in terms of their architecture, one can see some common features inside and outside of many mosques such as minarets, domes, ablution areas, prayer niche (mihrab), pulpit (minbar) and so on.
Muslims are obliged to perform the ritual worship 5 times a day. They are not required to attend a mosque for each of these prayers however in order to interact with the community they are encouraged to pray in congregation. Friday noon is the only time in a week when Muslims must definitely join the congregational prayer in a mosque after which they can continue their work, education or other commitments.
Azan or the call for prayer is a vocal announcement that one can hear from minarets 5 times a day. The call to prayer is made live -even early in the morning- by a person called 'muazzin'. The muazzins are usually chosen from people with loud and beautiful voices and trained over years to make this announcement beautifully and invite people to worship.