Final answer:
The main idea of this passage is that after being bombed, Hiroshima was rebuilt and became a thriving urban port.
Step-by-step explanation:
The main idea of this passage is that after being bombed, Hiroshima was rebuilt and became a thriving urban port. The passage mentions that the new Hiroshima has a modern skyline, shopping arcades, and a port that sends out consumer and industrial products to other cities. This shows that the city has gone through a transformation and is now a self-proclaimed City of Peace.