Over the last couple months, Pixiv artist Kurosshu has been posting a series of interconnected collages tracking the history of anime's mecha from Astro Boy and Gigantor to Nano Shinonome and Gundam AGE.
click on the links for larger versions
The beginning through the 70's - 41 featured
1980's - 83 featured
1990's - 110 featured
2000's - 100 featured
2010-2012 - 36 featured
throughout history - 400 featured