Defterdar Mosque

{{Short description|Mosque in Eyüp, Istanbul, Turkey}}

{{For|the namesake mosque in Kos|Defterdar Mosque (Kos)}}

{{Use dmy dates|date=January 2024}}

{{Infobox religious building

| building_name = Defterdar Mosque

| image = Defterdar Camii.jpg

| image_upright =

| caption =

| map_type = Turkey Istanbul

| map_size =

| map_caption = Location in Istanbul

| location = Istanbul, Turkey

| coordinates = {{coord|41.042|N|28.9376|E|region:TR_type:landmark|display=inline,title}}

| latitude =

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| religious_affiliation = Islam

| status =

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| architecture = yes

| architect = Mimar Sinan

| architecture_type = Mosque

| architecture_style = Islamic, Classical Ottoman

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| year_completed = 1542

| minaret_quantity = 1

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The Defterdar Mosque, or the Defterdar Mahmut Efendi Mosque ({{langx|tr|Defterdar Camii, Defterdar Mahmut Efendi Camii}}), is 16th century Ottoman mosque located in Eyüp, Istanbul, Turkey. It was commissioned by {{transliteration|ota|defterdar}} (chief finance secretary) Nazlı Mahmut Efendi (c. 1500–1546) and built by architect Mimar Sinan in 1542. Instead of a crescent, this mosque has "ink pot and pen" on top of its dome, representing the profession of the founder of the mosque ({{transliteration|ota|defterdar}} derives from {{transliteration|ota|defter}}, 'notebook, register', and the suffix {{transliteration|ota|-dar}}, 'doer'). The original pair was broken by a storm in 1997. Ten years later, on 30 May 2007, a new inkpot and a pen assembled on top of the dome of the mosque.Cumhuriyet (Newspaper), 3 June 2007, page 15 {{in lang|tr}}