Type the Sky by Lisa Rienermann is an alphabet formed of shapes buildings make against the sky when photographed from below.
According to the original post on German typographic blog Slanted (we spotted it on designboom), the alphabet was created by Rienermann while studying at the University of Duisburg-Essen.
"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).