As I have said in this Forum before, the orang enclosure in the Ape House at Cologne in 1973. A small tiled cell with no outdoor space. I think it was the same enclosure that Gerald Durrell excoriated in The Stationary Ark, although he not did name the zoo. It was demolished many years ago, I'm glad to say.
From memory I think the 'Ape House' at Cologne in those days was actually the Bird(or Tropical) House with some cages for Apes built into it ? It was in here I first saw the two baby mountain gorillas Coco and Pucker soon after their arrival circa 1968. Basel Zoo originally had a similar system of ape cages built at either end of their Bird House too-presumably because of the warmth available. These were also similarly tiny though the gorilla ones had a small outside cage also- it was in here that their first four(?) Gorilla babies were born.