Final answer:
The climax of Athens's city occurred during its golden age after the defeat of the Persian invasion. This period witnessed remarkable advancements in various fields and the construction of iconic architectural landmarks like the Parthenon.
Step-by-step explanation:
The climax of Athens's city can be identified as the golden age that followed the defeat of the Persian invasion in 480-479 BCE. During this period, Athens experienced significant growth in various fields such as drama, philosophy, literature, art, and architecture. The construction of the Parthenon, which symbolized the birth of democracy and showcased extraordinary architectural refinement, was a notable achievement of this climax.