The speaker announces a big project about cities, and the poem becomes a kind of meditation on how to live in them. His main idea is that you need distance to understand a city. Go to a desert or a mountaintop, then come back. From far away, skyscrapers look like perfect sculptures pointing toward God. Up close, they feel like places full of hidden sadness, with a million people having cried in the streets below.
The speaker's feelings are mixed. He says he loves and admires cities, the way we admire giant animals, but he stays cautious. Without a reason to be there, they can seem like traps. Still, the ending is hopeful and humble. He believes every path is a path of learning, and that we must walk gently or we will "step on other people's hearts." Calling the city a school he will someday graduate from gives the poem a calm, respectful mood, wary but accepting.