Secret meanings of colors according to a Victorian work of synesthetic mysticism called Thought-Forms (1901). A future article on the book is in the works, but for now you can read more about synesthesia here.
A hunting cheetah from “An Azappo Archer with a Cheetah,” Jacopo Ligozzi, circa 1575. More on war animals here.
Al Capone’s jail cell, and other secrets of Eastern State Penitentiary.
Carl Sagan’s childhood drawings about space are just as endearing and idealistic as you’d imagine.