Also called the Teeth of Mordor. Two towers situated on either side of the Black Gate of Mordor. The towers — known individually as Carchost and Narchost — were originally constructed by the men of Gondor after Sauron's defeat in the Second Age to guard the entrance to Mordor, but were taken over by Sauron in the later Third Age, having been abandoned sometime after the defeat of King Ondoher in 1944 to the Wainriders, as the Towers are stated to have been manned before the Battle.
Tolkien's writings leave it unclear which tower was located on which side of the Morannon. However, Carchost appears to have stood to the eastern side and Narchost on the western side. Carchost is a Sindarin name that means "Tooth Fort", a compound of carch (meaning 'tooth or fang') and ost (meaning 'fortress'). Narchost is a Sindarin name that means "Fire Fort". The towers were destroyed in the War of the Ring with the defeat of Sauron following the destruction of the One Ring. Their collapse is shown in Peter Jackson's film interpretation of Return of the King.