You've probably walked past this dozens of times if you've visited the Square, but did you know that this piece of public art- Omphalos- is by the same artist who designed the Thermopylae sculpture outside of the JFK Building in downtown Boston and the 60' tall Fountain waterfall in the Copley Place Mall? The artist is Dimitri Hadzi, and he was a professor of Visual and Environmental Studies at Harvard University.
"Omphalos," by the way, means navel... or belly-button. In Ancient Greece the Omphalos also meant the center of the cosmos, which could apply to many different places but was usually associated with the Oracle at Delphi. Pretty heady stuff for a jumble of rocks in the middle of a busy intersection!