Sing now, ye people of the Tower of Anor,
for the Realm of Sauron is ended for ever,
and the Dark Tower is thrown down.
Sing and rejoice, ye people of the Tower of Guard,
for your watch hath not been in vain,
and the Black Gate is broken,
and your King hath passed through,
and he is victorious.
Minas Tirith means “Tower of Guard” or “Tower of Watch.” 
 Their eponymous watch for the evil of Sauron has paid off in victory.