It is an obelisk, and it was used by the ancient Egyptians to commemorate Dynastic achievement; for the Romans, it was used to acknowledge a superior foe defeated in combat.
Most obelisk's weigh hundreds of tons, there are 28 Egyptian obelisk's standing today, only 6 of them remain in Egypt. Rome possesses 11 and many more remain scattered throughout the littoral Mediterranean. Three of the most famous are in New York, Paris, and London.
The obelisks's in Paris, New York, and London were all moved two times before landing where they now reside. The previous author of these said obelisk's was Emperor Augustus himself.
Egyptian technology was extremely primitive, possessing only bronze chisels from which to work limestone used to build the pyramids, they had absolutely no metal tools capable of dealing with far harder granite from which obelisk's were quarried. Egyptian dynasties used dolerite balls (an igneous rock very much shaped and used like bowling balls) to pound the surrounding granite of a future obelisk. Working 12 hour days, a quarryman could lower a trench around the obelisk nearly an inch a day. Taking six months to separate sides from the quarried obelisk, the harder part was freeing the bottom, this was done by pounding sideways.
The world's foremost authority on obelisk's is Bob Brier, his book Cleopatra's Needles is now out from Bloomsbury. Here you discover how the Egyptians, Romans, Renaissance Vatican engineers and new world plutocrats moved these lovely megaliths.