Mordor

This is the dark realm of Sauron. Here is where the tower of Barad Dur was built. Mt Doom was also located here. Also the tower of Bared Bur is here. It was built on the second age by Sauron but was destroyed after Sauron was defeated and fleed to Dol Guldor. Later in the third age Saruman and the white council drove Sauron from Dol Guldor but he returned to his old fortress of Bared Dur in Mordor and so began his reign of terror until the ring was destroyed by Frodor and Sauron destroyed and the Dark Tower collapsed and and the evil in Mordor was gone. For that time.