The men (and they're almost all men) building Beijing in a bricks and mortar sense are less than full citizens in this city they're building. That's another thing China has in common with the United States.
American laborers are often undocumented migrants from another nation, while Chinese laborers are almost always migrants from another region in China. In the U.S., they live under the threat of deportation while their children receive free public school educations. China's hukou system means that laborers can work where they choose, but their children will have to go to school in the mother's hometown. Migrants' rights are improving in China, but they're improving slowly. Still, families are often separated, with parents working in cities and a child staying behind with grandparents.
The first photo shows a construction site in Beijing. The two buildings with blue roofs to the left of the site are temporary housing for the construction workers. There's some efficiency in this. Without the company housing, the workers would probably have to live a great distance away and face long commute times. I haven't been inside a building, but from what I hear it's probably small rooms with bunk beds. For summer, I think I'd prefer life in a tent (second photo). These guys are working at a smaller project in central Beijing.
I don't mention these conditions to evoke pity for them because that's the last thing these laborers would want. They're a long way from home working in tough conditions because they want to make a better future for their parents & wives & children and there's nothing in the world they could be prouder of. But I do worry about the people they've left behind.
Until I was about ten years old, my family moved around a lot. My father worked as a fast food restaurant manager (when he was starting out, that meant 7 days a week, ten hours a day, with Thanksgiving and Christmas off) and he elected to move up by transfering from one small town to another. Our family had a mobile home, a trailer, which was convenient. Whenever we moved, we'd just tape stuff down and call a trucker. We had a roof over our heads and food on the table and a mom who kept close tabs on us. And we got to see our father everyday.