According to the wiki - Steampunk is a subgenre of fantasy and speculative fiction which came into prominence in the 1980s and early 1990s. The term denotes works set in an era or world where steam power is still widely used—usually the 19th century, and often set in Victorian era England—but with prominent elements of either science fiction or fantasy, such as fictional technological inventions like those found in the works of H. G. Wells, or real technological developments like the computer occurring at an earlier date.
There is something about Steampunk cities that fits 3D animation so well:
The movie above was uploaded to YouTube by rkrehe20
See also Cities in Games - Midgar Visualisation.