I view private art collections as the ultimate thing to do in Berlin. This one is smaller than some others but the perfect tour. You have to reserve your spot well in advance, I was two weeks ahead to get a ticket. You have to know to walk into the courtyard and keep going or you might miss the entry. It IS private. The receptionist was very friendly and accommodating, the tour was a few people, just enough to allow dialogue around the artworks. There was some hands-on experience, there was plenty of interaction between the guide, the people and the artwork. There were great pieces by artists I studied in school decades ago, and some art from ones who I know are still making things today. One piece I remember from the cover of the art magazines of the early 80's, absolutely iconic piece. Great art. Great tour guide dedicated to bringing out the love of art, and an truly wonderfully low price.