This mosque is the one founded by Cezari Kasım Paşa in 1515, with a fine porch. It is small and not too far from Eyüp. I had just found several mosques closed for restoration and was delighted to find one without a fence, open, and with its old patina. Inside there are some not very interesting tiles in the mimber, but also a series representing the Kaaba at Mecca, Strolling through Istanbul indicates it is one of the first products of kilns at Tefkur Saray.

A note of caution: In 2019 I saw what are probably the original tiles of the tiles in the Istanbul mosue in a museum in Ankara. The link leads you to the first of that set, you can return from there.