There's a great scene in the first season of Mad Men where Don unveils a campaign for Bethlehem Steel. "New York, Chicago, and Detroit—all brought to you by Bethlehem," reads the copy. The client rejects the pitch, but the sentiment itself was hard to argue with: steel from those small rustbelt towns was feeding the growth of a kind of city never imagined before the 20th century.
Still, for most of us, it's hard to imagine that iconic landmarks like the Golden Gate Bridge or the Empire State Building ever didn't exist. In the same way we take these buildings and bridges for granted, we also rarely consider what cities were like before—or during—their construction. So, with that in mind, check out 20 of our favorite vintage construction photos below. And keep in mind, this is just a jumping off point—post yours in the comments, below.