Fat Margaret is listed in the UNESCO World Heritage as a part of Tallinn Old Town. The heart of KOKO´s architectural solution was a 700-year-old cog. Using ropes and a steel panel between the deck layers gave the impression as the ship is floating in the air. The projected starry sky above the wreck brings it out even better. The problem with limited space was solved by going one floor below the tower. This led to, among other surprises, the discovery of a medieval sewage tunnel. The cylindrical form of the tower was followed with a new staircase with a glass hydraulic lift in the middle.