In 2019 I received a copy of a book I had contributed several pictures to (including the front page), Ottoman Baroque by Ünver Rüstem. Of course I read it, but even after a superficial scanning of its structure I found, to my horror, that even after 60 visits to Istanbul there were a few mosques, baroque ones and fine examples at that, that I had never spotted, let alone visited. So during my 61st visit I corrected this, and the Beylerbeyi Mosque (also known as the Hamid-I Evvel Mosque) is one of them, and definitely a baroque one. Read the book for much more information.
It was built in 1777-1778, and was commisioned by Abdülhamid I in the memory of his mother Rabia Sermi Sultan, its architect was (maybe: the book describes how in many cases the actual architect was not known, but how a “chief architect” who oversaw all sort of building sites in town was often mentioned) Mehmed Tahir Ağa.
The dome has been replaced as the original one was damaged, and the two minarets were not in the original design but built in 1810-11. The mosque is on the side of the Bosporus in a neighbourhood called Beylerbeyi itself. In its front there is a courtyard, and in front of that fishermen are busy with their rods, surrounded by waiting cats. I add some pictures of the views along the shore, and a picture taken from a ferry showing the setting.
When I took a taxi from Üsküdar to get to the mosque the driver at some point headed inland, uphill. His navigation (as well as mine) indicated there was another Beylerbeyi mosque inland. If that exists at all it's not the one I was heading for, I had the impression the Hamid-I Evvel Mosque name is better known.