Henry Moore's Nuclear Energy marks the site where Enrico Fermi and his team achieved the first controlled, self-sustaining nuclear chain reaction in 1942. The sculpture stands on the University of Chicago campus, where that experiment took place beneath the old Stagg Field stands.
It is a quick stop, but a meaningful one if you are interested in science history. The abstract bronze form is often read as both a skull and a mushroom cloud, a fitting ambiguity for a monument to the beginning of the atomic age.