From wikipedia: Obelisk
The obelisk symbolized the sun god Ra, and during the brief religious reformation of Akhenaten was said to be a petrified ray of the Aten, the sundisk. It was also thought that the god existed within the structure.
It is hypothesized by New York University Egyptologist Patricia Blackwell Gary and Astronomy senior editor Richard Talcott that the shapes of the ancient Egyptian pyramid and obelisk were derived from natural phenomena associated with the sun (the sun-god Ra being the Egyptians’ greatest deity). The pyramid and obelisk might have been inspired by previously overlooked astronomical phenomena connected with sunrise and sunset: the zodiacal light and sun pillars respectively.
Does this not sound like Jim Sanborn’s description of the Corcoran installation?!
The Corcoran installation had some references to Greek mythology. There was a freestanding cylinder in the center of the room that was totally perforated with encoded text. Half of the cylinder was perforated text dealing with CIA operations. The other half of the cylinder dealt with KGB operations. The two existed side by side. A pinpoint light inside the cylinder projected these encoded texts, including the word Medusa, which was embedded in the texts, over the inside of the gallery, so that they covered every inch of its surface. It created an effect where Medusa’s gaze, represented by these bright texts, fell over one’s body as one walked through the room. There was a petrified tree in the room, a tree that had turned into stone. I felt as if the projected light was a visible ray that was as toxic as the information on that cylinder. It was a transformation from a text written to a text projected to a text that became toxic when it touched your body.
(see APEX of Kryptos Blog for more connections between Kryptos and Obelisks)