Argonath

[Meela]

I know I've already asked about the Argonath once upon a time, but I don't know if this has been asked. Forgive me if it has been.

I was watching Fotr when I suddenly wondered if the Argonath actually held any meaning. Apart from being decorative reminders of the kings of old or whatever. The first thing that hit me was that they were a sort of gateway to Gondor, marking the borders of the kingdom, and they were some form of guards or protecters.
Does anyone know the actual meaning of them, if there is one?

[Tar-Palantir]

I believe one is Isildur and the other is his brother Anárion. They mark the old border of Gondor.

[Meela]

Oh, so they are border markers... thanks!