Regarded as the oldest zoo in Asia, Trivandrum Zoo occupies a total area of 22 ha, and has woodland, lakes, and lawns. The Thiruvananthapuram Museum and Zoo was established way back in the 1800s by Swathi Thirunal Varma who rules Travancore during the ancient times. It was later formally established as a zoo in 1857, and was initially opened as recreational hotspot.
The zoo today has lost quite a bit of land, and is focussed on conversation of wild animals. You can expect a total of 82 species here from around the world, and these include the lion-tailed macaque, the Nilgiri langur, Indian rhinoceros, Asiatic lion, royal Bengal tiger, white tiger, and leopard.
The zoo also includes a snake farm called 'The Reptile House', which exhibits both poisonous and non-poisonous snakes. It also houses 7 Anacondas too. Animals in this zoo are usually released in an open enclosure from their century-old cages, and can be easily viewed at a close distance.
According to en.wikipedia and oldest.org.