Just found out about this today, described to me as one of the lost masterpieces in art history, Kurt Schwitters Cathedral of Erotic Misery, or Merzbau, is the culmination of hoarding and creativity. In his parents house in the suburbs of Hanover Schwitters transformed six (or maybe more) rooms of his family home. The evolution of the space taking place very gradually from around 1923 til 1937 when Schwitters fled Nazi Germany. Unluckily, the house was destroyed in 1943 by a bombing raid, so very few photographs were ever taken. Here’s the best one I found.