Dark Tower

Also known as Barad-dur, it is the tower of Sauron in Mordor.

It is located on a spur of the Ash Mountains that form the Northern boundary of Mordor.

History
The battle of the Last Alliance was fought under the Tower where Gil Galad and Elendil were killed.

When the Wizards entered Dol Guldur, Sauron simply returned to his old fortress in Mordor and raised the Dark Tower once again.

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