Sphere Within Sphere (Sfera con sfera) is a bronze sculpture by Italian sculptor Arnaldo Pomodoro.
Versions of the sculpture (diameters vary) can be seen in many settings worldwide, including:
Also note, this 'may' be a depiction of a concavity concept, that demonstrates a concave earth perspective, which also contains a celestial sphere within the center. Alternatively, it may also represent the world breaking out of the Ptolemaic view of the heavens, a nodding reference to both Copernicus and Galileo.
References
Sphere Within Sphere Wikipedia(Text) CC BY-SA