Mexico City has one of the biggest urban parks in the world, Bosque de Chapultepec (Chapultepec Park). This sprawling city forest is divided into three sections, two of which are full of popular museums and attractions. The third section, though, is a different story altogether.

This neglected western section of the park is a huge swath of dense forest that is unreachable in some parts, with deep cliffs and ravines and even some caves. It’s prohibited by law to build there, and is so desolate it can be scary and potentially dangerous to go at night. It’s also swirling with urban legends, adding to the eerie mystique.

But during the 20th century, there were some major attractions in this part of Chapultepec, namely a wooden playground called Woodland, an aquarium and marine park called Atlantis, and a water park called La Ola, with a wave pool and water slides. All these places are abandoned and in a state of decay now. Over time there have been various projects to try to rescue this space, but none have prospered.

The last and possibly strangest feature here is a sort of cemetery for concrete animal sculptures. In the 1970s, these creations were part of an urban area for children designed by sculptor Alberto Perez Soria. He developed a series of concrete, animal-shaped play objects—turtles, fish, rhinos, lions, horses, bears, and so on—inspired by the fascination and astonishment that animals engender in children.

The play sculptures were made to be reproduced throughout the country and they remained in use for more than 40 years before they began to be replaced by the plastic and tubular sets. The abandoned animals are now scattered in this lonely corner of Chapultepec. Made of concrete with cast iron rods inside, each must weigh hundreds of pounds, so it’s likely they will be here for a long time to come.