Haven't gotten around to the Nag-Hammadi as of yet, but it's in my backlog.
Pistis Sophia is a gem though.
It certainly is/was. We went in 2009 to Turkey when Pope Benedict was there at the same time
I insisted we stay away from him, because he wasn't particularly liked either considering his negating Turkey for (back then) joining the Euro group.
So we were 1 week behind whereever he went, we ended up there a week later, same tour places at least in Istanbul including St. Nicklalus church & perhaps he went to Rumi's tomb, (I don't think he did)
Here is the 4 D virtual tour for whoever is interested in this spectacular complex:
http://www.3dmekanlar.com/en/hagia-sophia.html
Did you know its now been officially turned into a Mosque? No longer the Christian church coupled with Mosque, but an official mosque.
I think (personally speaking) that is because of President Erdogan who is really more orthodox then Turkey ever had before since before WW2 and makes it harder to share the two great anceint religions.
Oh well......