The Museum of Soap and the History of Dirt in Bydgoszcz is one of the most unusual museums in Poland. Housed in a historic tenement house on Długa Street, it tells with humour how people cared – or failed to care – for hygiene over the centuries. Visitors learn what old bathhouses looked like, what people washed with before soap was invented, and how cosmetics are made. We created a mobile app and an audio guide system that lead visitors through the exhibition and bring this surprising history of cleanliness to life. It is a great choice for a visit with children.