Other options for things to see

Blue Mosque

Might be worth checking if it’s still under renovations inside

Basilica Cistern

Surprisingly cool to see, doesn’t need to take too long

Grand Bazaar

Noteworthy, but a bit repetitive to spend a long time. Rick Steve’s has a walking tour for this in his book.

Topkapi Palace

The main Ottoman palace, would probably need some time for this

Spice Market

Included in Rick Steve’s Old Town Back Streets walking tour

If you have time, can take the Old Town Back Streets walking tour back to the Golden Horn