Final answer:
The Pantheon in Rome as rebuilt by Hadrian was not a celestial observatory, but it was a tribute to the gods, a symbol of Roman power, and a shrine for the Imperial cult.
Step-by-step explanation:
The choice that is NOT a possible meaning of the Pantheon in Rome as rebuilt by Hadrian is c. Celestial observatory. The Pantheon was indeed a tribute to the Olympian gods, a symbol of Roman power, and a shrine for the Imperial cult, as its design reflects a monumental architectural feat symbolizing the divine cosmos and the power of the emperors. However, there is no historical evidence to suggest it was used as a celestial observatory as opposed to the clearly indicated religious and political purposes.