We call it the "Great Wall of Tonga"...
Retaining walls and terrace at our house in Kaaawa
...Because it took what seemed like an entire Tongan village to do the job. I held my breath the whole time they were working, fearing the job wouldn't get done or wouldn't get done right, despite a somewhat reassuring conversation with the engineer who did the drawings and a building permit in the name of a licensed contractor. In the end, all worked out relatively okay. The scale of this photo is deceptive. The lower wall is about seven feet tall, although it doesn't look that big in the photo, and the upper wall is a similar height. It extends well over 100 feet along the side of our house, where erosion had been making serious progress along a long stretch of the hillside, with visions of the house being undermined at some point in the not all that distant future. This wall, though, appears here to stay.