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Founded in 1901 by the physician and biomedical scientist Vital Brazil, the Instituto Butantan was originally involved in fighting outbreaks of bubonic plague before evolving into its current guise: a research facility that specialises in venomous animals and produces around 80 per cent of Brazil's vaccines.
Highlights include the largest serpentarium in the country and the Biological Museum. The former is a sunken outside area surrounded by glass walls, where you can watch rattlesnakes, pythons and pit vipers basking in the sun (or hiding in their shelters) from a safe distance.
The Biological Museum houses a wider selection of native and imported snakes, as well as spiders, scorpions and fish. Highlights include anacondas, a white Burmese python, potentially deadly coral snakes, as well as tarantulas.
The place has an endearingly low-tech, low-budget feel – but don't worry, those scary critters are safe behind substantial glass barriers. The museum is popular with children, and has colourful, cartoon-style signage in the Biological Museum and a selection of cuddly snakes in the gift shop. The monkey house, closed for refurbishment until further notice, is also, unsurprisingly, very child-friendly.
On a dry day, the extensive, leafy grounds make for a pleasant stroll among local flora and period buildings. A portion of the museum (the Museu da Rua, or Street Museum) is located in the gardens – there's a walkway of illustrated posters in Portuguese and English that take you through key episodes in the Institute's history.
Also noteworthy are the Historical Museum, with an array of antique equipment used in anti-venom research and production, and the Museum of Microbiology, which combines interactive multimedia, microscopes and models to appeal to a wide cross section of visitors.
If all those pesky kids tapping on the glass just a little too vigorously bring you out in a cold sweat, take comfort in the fact that should the ultimate Hollywood-style snake breakout occur, those unfortunate enough to fall prey to one of the Institute's many dangerous species can pop into the on-site hospital for a shot of anti-venom. Convenient, that.