Sauron settled in Mordor in the Second Age of Middle-earth, and it remained the pivot of his evil contemplations. He built his great stronghold Barad-dûr, the Dark Tower, near the volcano Mount Doom (Orodruin), and became known as the Dark Lord of Mordor. He discovered how the Rings of Power were made from the Elves of Eregion in Eriador, and secretly forged the One Ring in Orodruin. He then set about conquering Middle-earth, launching an attack upon the Elves of Eregion, but was repelled by the Men of Númenor.