It is common for medium-sized and large empires to feel a happiness crunch in the middle game. There are just so many cities, and so many people in those cities! This is when well-placed Entertainment Complexes with Zoos in them really come in handy. A single one of these may provide Amenities to 3-4 cities, if situated correctly! Use the same logic when placing them as when you plan the placement of your Industrial Zones.
The Zoo also adds Science yield to Rainforests and Marshes within its city's territory. Build Entertainment Complexes in jungle cities to get a solid scientific boost come the Industrial Era. This is especially useful for civilizations such as Brazil and Kongo, whose scientific side may suffer due to their starting bias.
The oldest known menagerie (or “zoological park,” i.e., zoo) has been excavated at Hierakonpolis and dates to c. 3500 BC; according to archaeologists, it contained hippos, elephants, hartebeest, baboons, and wildcats. In the 12th Century BC the Chinese empress Tanki had a “house of deer,” and the later Wen of Zhou established a 1500-acre menagerie. Alexander the Great had live specimens of unusual animals sent back to Greece to be displayed, and most of the Roman emperors had extensive collections of animals for the citizens to ogle. Humans have always been fascinated by watching caged animals, but no one is quite sure what the animals staring back at the humans are thinking; probably better not to know. The oldest existing zoo, the Tiergarten Schoenbrunn in Vienna, evolved from the exotic animal collection maintained by the Habsburg dynasty and was opened to the public in 1765 AD. Whipsnade Wild Animal Park in England opened in 1931 as the first drive-through “safari” park … a supposed “advance” over the traditional zoo full of cages.
What Could Possibly Go Wrong?
Have an improved Amber resource in a city with a Zoo and an Archaeological Museum at the start of the turn.