About the background wallpaper
The background images belong to a 1508 notebook by Leonardo Da Vinci containing short treatises, notes and drawings of a wide range of subjects from mechanics to the moon. This images were possible thanks to The British Library who made this and other great books available online.
The Library's site allows you to view the original manuscript written in Leonardo's own (backwards) handwriting.
Da Vinci was an Italian architect (and painter, sculptor, musician, engineer and scientist) who meticulously recorded his designs on paper.