This video is a little slow and seemed a bit technical at first, but the payoff is worth it.

Dirt is probably the cheapest and simplest construction material out there, but it's not very strong compared to other choices. Luckily geotechnical engineers have developed a way to strengthen earthen materials with almost no additional effort - Mechanically Stabilized Earth (aka MSE or Reinforced Soil). If you look closely, you'll see MSE walls are everywhere.

Will be cool to notice these constructions all over the place now that I know what they are.