Type the Sky by Lisa Rienermann is an alphabet formed of shapes buildings make against the sky when photographed from below. Update: this project is included in Dezeen Book of Ideas, which is on sale now for £12.
"It began with the Q," she tells Slanted. "I was in a kind of courtyard in Barcelona. I looked upward and saw houses, the blue sky and clouds. The more I looked, I saw that the houses formed a letter Q."
The following is translated from Slanted's original German: "She then set out to find more letterforms, spending weeks only looking upwards. The more difficult letters such as Q and K were the easiest to find, she says, but admits that PhotoShop helped here and there."
The alphabet was presented in a booklet contained in a box (we think, our German isn't so good).