This is a place to demystify the idea that snakes are malevolent animals and to lose that primal fear that we seem to naturally have.
It's very cool to see children going there, enjoying and learning about the great amount of research made to benefit humanity from serpent venom.
The place is kind of art deco. Many vaccines were produced there - in fact, Instituto Butantan participated in the development of many combined vaccines - and also antidotes for all sorts of venom.
There's also a learning part of the experience in which you can get to know and even touch the snakes, see them in a reproduction of their natural habitat, just hanging out. It's pretty cool. You'll end your visit wanting to buy a stuffed animal in the form of a snake!