Riddonkulous

I rise where footsteps fade to dust, A silent keeper built on trust. No voice have I, yet still I speak Of hands long gone and power at peak. A shard of earth that dares the sky, A question cast in stone: But why? Am I a marker, grave, or throne, Or something meant to stand alone? Four sides I often choose to show, With edges straight and tip aglow. At dawn I stretch, at dusk I fall, A shifting shadow over all. Not quite a tower, not quite a spear, Yet both ideas may linger near. I pierce the heavens without a sound, A rooted spike in sacred ground. What am I, unmoved yet bold, A story carved in ages old?