Back here on Earth, there are also some sizable Engineering projects that are either under way, or planned:

  1. Back during the cold war, the United States looked into getting a Peace Dividend out of its nuclear weapons in terms of large-scale earth-moving capability. Codenamed Project Plowshare, the idea was to use nukes to carve out new harbors where none existed before. I seem to remember that the Soviets actually did use this method once, with spotty results.
  2. And speaking of nukes, the Chinese have looked into using them to blast a hole through the Himalayas in order to divert the output of a large river onto Chinese soil. As the river currently irrigates much of northern India, this has the Indians worried.
  3. And speaking of the Chinese, let's not forget the Great Wall of China, which was (and I think still is) the largest structure ever built by humans...and back in antiquity, too!
  4. Hong Kong's new airport might also deserve a mention here. Since there's not enough real estate on the island to handle the necessary air traffic, they're building the whole thing on a new man-made extension to the island.

Ok, now back to the sci-fi. In addition to the space elevator, Kim Stanley Robinson's Mars trilogy also makes use of a soletta to heat Mars to more terrestrial levels. This is basically a really really big array of orbiting mirrors, focused on a central reflector of about 1/2 degree diameter as seen from the surface. The result is an earthlike sun for a planet farther out in orbit.

Kind of a spoiler follows.....

Later in the series, the soletta is removed from martian orbit, and becomes an enormous parasol for Venus, as the first in the terraforming of that planet.