Inspired by the Eiffel Tower, a Russian scientist as far back as 1895 suggested an elevator to space. It's far from becoming a reality—the technical challenges are close to insurmountable—but it's in the air (so to speak).
The basic idea is to run a fixed cable from a point on the Earth’s equator to a space station directly overhead, or even to the moon, with cars running up and down the cable carrying people or freight. Of course, the cable has to be both light and strong, and all the satellites and asteroids out there have to miss it every time around.
Every once in a while I am struck by what other people are thinking about while I'm reading Robert Lowell & practicing kata.