What is the whole story behind Minas Morgul, Gondor, and Mordor?

[Galadriel55]

Well, we don't really know much what exactly was inside Minas Ithil, but whatever it was, Sauron probably destroyed it and changed everything into orc barracs and storages of weapons.

I hate to sound sardonic, but did it ever occur to you, during these long years, to google "Minas Morgul"?

Ah, well, googling takes so much time! Especially for Tolkien - every website has contradictive information about who, what, where, when, etc. It's soooo much easier to just ask a friend who knows.