Here is a panning shot of one of Eternia's greatest technological wonders, the Great Eternian Dam from "Island of Fear", the season two He-Man episode with the strikingly original plot! This is a great piece of Filmation artwork, and this assembled image shows just how big the dam is. What is unfortunate is that the series never revisited the dam again, or even mentioned it in passing. Maybe this is what makes "Island of Fear" such an original episode?
(click on the image to see it at full-size)