It points south from the inner side of high ground
With it's own high heights and lower than low places.
It is known from afar that by greater magics it is bound
and that it awaited the return of it's lord's dire graces.
Barad-dur
Barad-dûr, also known as the Dark Tower, was the chief fortress of Sauron, on the Plateau of Gorgoroth in Mordor.
Tolkien Gateway: Barad-dûr