Conceived as a candid diary, this remarkable book documents the 1,423 days that it took to design, build, and inaugurate a beloved architecture and fashion destination. From the moment the up-and-coming French-Moroccan practice Studio KO received a call from YSL's longtime partner Pierre Bergé to the opening of the museum's doors in 2017, one month after Bergé died, the entire process of bringing the building to life - its commission, the creative process behind it, and its construction - is told and illustrated here as never before.