Since the beginnings of the city, the level of the Market Square has raised (in some places by over 5 metres). Underneath there are large basements and passages linking some of them, such as the one linking the Town Hall Tower with the Sukiennice. Since 2010, a museum has been opened there, offering tours of the underground vaults.
The archaeological layers of the Main Square reflect 1000 years of history. In order to see how Krakow looked like in the late Middle Ages, one has to go underground. The Rynek Underground permanent exhibition showcases close connections between the mediaeval Krakow and other European cities of that time. It also offers an opportunity to observe the city from a unique perspective. The underground is a division of the Historical Museum of Krakow.