"Why do architects always wear black?" Cordula Rau was asked this question by an automotive industry manager during an architectural competition. Although an architect herself who also wears black, she didn't have an answer off the top of her head. She decided to ask other architects as well as artists and designers. Since 2001, she has been collecting their handwritten replies in a notebook.

In 2008, these were published in a small work – black-bound, of course. For its new edition, this legendary collection has been expanded to include new amusing, pragmatic and subtle explanations: "Read it – but please don't ask me why again architects wear black!" (Cordula Rau)