Final answer:
Emperor Hadrian ordered the construction of the Pantheon, and he redesigned it on a larger scale after it was damaged by fire. The false inscription attributing the building to Marcus Agrippa was added by Hadrian as a tribute to his predecessors.
Step-by-step explanation:
The Pantheon was built under the orders of Emperor Hadrian. After the original Pantheon was damaged by fire, Hadrian decided to rebuild it on a larger scale. He is credited with conceiving, and possibly designing, the new structure as a display of his power and beneficence. The false inscription attributing the building to Marcus Agrippa was installed by Hadrian to honor his predecessors and gain favor with the gods.