I can't say for sure, not being there and all, but i can make an educated guess.
From what i have been shown, i can say that they probably used a sand pit, gravity, and man power. They would have put the ____ stone at the bottom of a large structure filled with sand with a ramp leading up to it. they would have aligned the edge of the obelisk at the top of this ramp with the turning groove at the bottom to the best of their ability, and slowly dug the sand out from the structure, eventually having to use their hands to clear the sand from under the obelisk after tools would no longer fit. Then, they probably used man power to lift the obelisk into it's upright position.
I do NOT claim this answer as my own. i based it off this: http://www.YouTube.com/watch?v=xFcMWUeRePw&feature=player_embedded
I hope this helps, even if I'm wrong.
obelisk
An obelisk is made from a solid piece of grey or pink granite.
penis
No. Because Fiendish Chain targets a monster, Obelisk the Tormentor will not be affected by it.
if you sacrifice ra and slifer while obelisk is on the field obelisk wood have infinite attack and nothing can stop him
The Washington Monument is a fine example of an obelisk. Just look at that obelisk!
hexagonal obelisk
Obelisk is a noun.
obelisk
Wychbury Obelisk was created in 1758.
Obelisk International was created in 2006.
Dalhousie Obelisk was created in 1850.
The Black Obelisk was created in 1956.
Obelisk Press was created in 1929.
Kagul Obelisk was created in 1772.
Obelisk the Tormentor has 4000 ATK.
I don't know who constructed the obelisk because you are not asking specifically WHICH obelisk. There are many obelisks in the world to choose from.