There are several circles in Paseo de la Reforma. All but one have a monument:
Monument to Columbus, XIX Century:
Monument to Cuauhtémoc, the Aztec's last emperor, XIX Century:
The Palm (and the Mexican Stock Exchange building)
The Angel of Independence, 1910, Mexico City's official landmark:
And Diana Cazadora, XX Century (The Huntress of the Northern Star is it's real name):