The Argonath in art and film.
These gigantic statues appear in J.R.R. Tolkien's The Lord of the Rings books. These statues were carved about 500 years before the events of the novel. They were "huge" statues carved in the likeness of Isildur and Anárion (the sons of the first king of Gondor, Elendil.) Tolkien describes the statues as "tall and sheer" and the color of the rock they were carved from as grey. Each stood on a pedestal "in the deep waters" -- which indicates that they were not attached to the canyon wall but freestanding. The rest of Tolkien's description is minimal: "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."
However, it is clear that the Argonath are NOT taller than the cliffs behind them. Tolkien says that the "dreadful cliffs" "[s]heer rose...to unguessed heights on either side. Far off was the dim sky." This is in stark comparison to the canyon prior north of the Argonath, which is deep but had sloping sides on which tumbles of broken rock and the occasional tree and shrub grew.
The canyon beyond the statues is the actual Gates of Argonath, not the statues themselves. The chasm was so deep now that almost no light could be seen overhead, and so narrow that the water was rushing extremely fast. Everyone was afraid, except Aragorn. It jogged westward after a while, so not even the exit of the canyon could be seen. Then it went due south again, and the end could be seen like a brilliant, vertical, narrow shaft of light.
Nen Hithoel, the oval lake beyond, was surrounded by "steep gray hills clad with trees". These are clearly described as hills and so must have been much, much smaller than the canyon the Fellowship passed through. "At the far southern end rose three peaks. The midmost stood somewhat forward from the other and sundered from them, an island in the waters..." The eastern and western peaks could not have been much taller than the hills nearby, however, because they can be easily climbed (as we see in the chapter "Breaking of the Fellowship"). They probably were much less steep, too.
So those are the Argonath. How have they been depicted in art and film?
First up, the Argonath as they appear in artwork from the early 1970s by the Brothers Hildebrandt. You may not know who the Brothers Hildebrandt were, but in the 1970s they were the go-to guys for fantasy artwork. They were twin brothers born in Detroit in 1939. They were professional illustrators and graphic artists, and had a deep and abiding interest in Tolkien. The first Tolkien calendar came out in 1969, and another one did not appear until 1973. The first calendars were illustrated by Tolkien himself, with other art from Pauline Baynes, Tim Kirk, and Philip Helms. The first Brothers Hildebrandt calendar came out in 1976, and they did them every year until 1982.
Here are the Argonath as they appeared in Ralph Bakshi's 1978 animated film, The Lord of the Rings.
Artist John Howe did illustrations of scenes from The Lord of the Rings in the 1980s. Here is his Argonath. He later worked alongside Alan Lee on the Peter Jackson films.
Here are the Argonath in the Peter Jackson film.
Lastly, this is Canadian artist Ted Nasmith's take on the Argonath. This appeared in 2003, although Nasmith was illustrating The Lord of the Rings in the 1980s and 1990s. He was asked to work on Peter Jackson's films, but could not do so due to personal issues.