One of the most important inventions in the field of graphic arts was perspective: the ability for artists to render three dimensions on a two-dimensional field. Attempts to create the illusion of depth began in earnest in ancient Greece, but true perspective was often eschewed in ancient and medieval art for stylistic reasons.
Isometric projection is one of the simpler ways to create the appearance of three dimensions. Here, I'll show you; although, the limitations of ASCII pose additional challenges.
I recall the isometric perspective fondly for one major reason: it was in my video games. Civilization II relied on isometric, as did X-COM: UFO Defense and SimCity 2000 - just a few of many. It's not used quite as often anymore, since graphical rendering capabilities have increased to a point where other mechanisms for creating the appearance of three dimensions are feasible.
This three-quarters photograph of the TD Canada Trust Tower, part of Brookfield Place in downtown Toronto, is as close to isometric as I can reasonbly get to. For complete accuracy, I'd need to have a flying camera - isometric games generally went with the bird's-eye perspective.
I, the copyright holder of this work, hereby release it into the public domain. This applies worldwide. In case this is not legally possible, I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.