The 16th century çeşme (fountain) belonging to the Üçbaş complex (in the Fatih district).
(the calligraphic inscription is Late-Ottoman, probably 18th century).

A çeşme (a kind of fountain) is a piece of architecture which pours water into a basin to supply drinking water.
They were connected to springs or aqueducts. Until the late 19th century most ‘çeşme’ operated by gravity, and needed a source of water higher than the fountain, such as a reservoir or aqueduct, to make the water flow.

Correspondent: J.M.Criel, Antwerpen.
Sources: Website of ‘megaplatform.org’ & Wikipedia .