The Poznan Stare Zoo (“stare” means “old” in Polish), established in 1874, is the second oldest zoo in Poland, and it still maintains its original 19th-century cages. The use of cages with bars often conjures up images of a prison, which can send the message that zoos have not been updated or modernized. However, from a practical standpoint, cages are one of the best materials for animal captivity. They are inexpensive, safe, easy to clean, and can expand animals' living space by providing vertical climbing areas. On the other hand, modernized zoos tend to use glass or moats to create the illusion of animals living in unlimited enclosures, which reduces the emotional distance between visitors and animals. The visible barriers, such as ropes or bushes, are simply a reminder for visitors not to cross and signify the boundary between nature and civilization. This sends a very different message from the traditional iron bars.