What is the symbolic significance of Mrs. Slade’s “eyes ranging ...Colosseum”? Did she think that girls away with sentiment and moonlight?
Mrs. Slade and Mrs. Ansley are engaging in their own mortal battle. They are fighting as skillfully as the gladiators of the Colosseum once fought, but much more subtly. Their weapons are words and deceit. When Mrs. Slade's "eyes rang[e] the ruins which faced her to the long green hollow of the forum, the fading glow of the church fronts beyond it, and the outlying immensity of the Colosseum," the conflict begun in the past is renewed in the present.
The Colosseum is an important symbol in the short story. It is the place where years ago, Alida Slade had sent Grace Ansley on what she thought was a futile mission to meet Slade's fiance. Grace would think that Delphin Slade was meeting her there but, Slade had hoped, would find nothing but the damp air that would result in Grace's catching "Roman Fever." Alida Slade actually plotted Grace's sickness, or even death, much like their great aunts had done to each other before.
So the Colosseum was the former battlefield between the two women. But it was also a place of moonlight and romance--at least for Grace Ansley. It symbolizes the competition between the two for the same man, a competition that spans generations of women and probably will continue with the two women's own daughters.
In this particularly competition, Grace Ansley wins--both in the past and the present. She did not catch Roman fever and she did actually meet Mr. Slade there. At the end of the story she delivers the devastating knock-out punch--that her child was fathered by Slade's husband.