Who knows when the Eurasian otter enclosure was built? A small outdoor one on the top of the hill, with an underwater view and many boulders? From the design it appears something like 1960s-1970s.
There is an article about this enclosure in Volume 12 of the International Zoo Yearbook (1972). Although no specific dates are given for the construction, the animals arrived in 1970 so it's probably safe to say 1969/70.
