J C

Hidden away, surprisingly, right outside of sultanahmet, this is a cistern that was in use during the byzantine period and its clear from it's appearance. The really nice thing is that it is never crowded at all, so you'll never have to wait in line. Tickets aren't very expensive and, as mentioned, it is not full of people which makes it nice to explore. On the downside, it's more barren and doesn't contain actual water like the Theodosius or basilica cistern. During the ottoman period, it was used as a storage facility and workshop. Overall, it's a cool and less touristy cistern in a very touristy area.
It's worth a visit but is not quite spectacular.

One of the hidden gems in Istanbul! It's a very cheap museum (100TL) and you are able to explore virtually the entire fortress. See the golden gate, walk around the area in front of it, enter the dungeons, climb to the top of the wall and get a panoramic view of the area and the Marmara. Simply fantastic and worth the time.

Very pretty church. It's the center of orthodoxy but appears modest from the outside. On the inside, there are some relics and the altar area is very elaborate.

Really cool to see the walls go on and on. Nice parks along the walls. Wonderful

Where to start? This has to have been my favorite church of the 7 pilgrim churches of Rome. It's not difficult to get to as the blue line takes you right there, and the courtyard + interior are amazing. I cannot believe how few visitors it gets as it is as impressive as St. Peter's in my opintoon. I can't adequately express just how striking the interior of the church is..it is massive, and the sculptures, mosaic and portraits are wonderful. You are also able to see the area where St. Paul is buried.. just take an hour or two to spend here and to pray (and go to confession! - available in many languages at many times per day). You won't regret it. A real gem.