The Argonath - The King Stones.  Great statues of the sons of Elendil guarding Gondor's nothern pass through the River Anduin.

"'Behold the Argonath, the Pillars of the Kings!' cried Aragorn.  'Fear not!' he said.  'Long have I desired to look upon the likenesses of Isildur and Anárion, my sires of old...'  The left hand of each was raised palm outwards in gesture of warning; in each right hand there was an axe; upon each head there was a crumbling helm and crown.  Great power and majesty they still wore, the silent wardens of a long vanished kingdom." ~The Fellowship of the Ring, Book II, Chap. 9 (The Great River)