Citizens of Puebla City, located in the southeast of Mexico, told folktales about a mysterious network of tunnels hidden beneath the city. For hundreds of years, no such tunnels were ever found, so people assumed that they were nothing more than the stuff of legends. But then in 2015, a construction crew discovered a very real tunnel beneath the city. Crews began excavating the site and eventually discovered around six miles of tunnels snaking under Puebla’s streets. The tunnels, which are believed to have been constructed from the 16th century all the way through the 19th century, have been opened as a tourist attraction today. On the other hand, here are some forbidden places no one will ever be allowed to visit.