They both are trying to show how people come together to pay tribute to the men who died while in war. The photo shows tribute while the poem is showing the reader the emotions of a visitor.
The central idea of both the photo essay and the poem is that the Vietnamese War took hundreds of lives away from the United States of America. It ripped men from their loved ones, family, friends, and it left a wave of death in its path. Along with its wave of death, it scarred many people, especially those closest to the men that died fighting.
It means to leave and wait wait and notice how nothing changes while you're gone. I hope this helps! If it does, please mark my answer brainliest, I need it to level up! <3
In the passage the poet describes London using personification, the city appears mostly as a "helper" since it gives life and shape to various people who live there.