You might find it hard to believe, but this building, up until 2002 was... a factory called L'atelier des cendres - the ashes workshop - (you can still see the name above the door). This company used to recycle the "ashes" of jewelers as a way to collect what was left of gold and silver. It was totally renovated in 2013 by Uniqlo, the Japanese clothes manufacturer who kept most of the old features (including the stunning chimney and the beautiful staircase). It's definitely worth a visit if you happen to be in Le Marais.