Obelisk of Sesostris I, XII dynasty, Middle Kingdom. An obelisk is a stone made monument, much like a column but supporting nothing. Obelisks were erected by Ancient Egyptians for an commemoration.Obelisks were usually made of a single piece of stone. A bird's eye view of obelisk is square and this structure has gradually tapering four sides and its ends in a pyramidal top.belisk of Sesostris I, XII dynasty, Middle Kingdom. An obelisk is a stone made monument, much like a column but supporting nothing. Obelisks were erected by Ancient Egyptians for an commemoration.