From the outside, you can only see normal buildings, but you may be surprised to find a large underground city beneath them. It is located in the southern Polish city of Wieliczka and is known as the Wieliczka Salt Mine. Although mined, it is also known as the Wieliczka Underground City because of its vast, underground network of underground capitals.
From the outside, it looks like this. This is the entrance to the Salt Mine.
This salt mine is a historical site that has been used for salt production for thousands of years. At that time, salt water was heated in clay pots to obtain salt. Around the 13th century, mines began to be discovered after the accidental discovery of a solid salt mass. Local excavators used Western European technology. The salt industry was operated by the Żupy krakowskie company from the 13th to the 20th century.
The main mining site was excavated during the reign of 14th-century Polish King Casimir III. Network channels and chambers were also dug in the salt mines. The king took special care of the miners and built a hospital near the mine to treat them if they were injured or injured.