It is a natural monument. The caves are built of Cenomanian sandstone from the Cretaceous period, i.e. almost 100 million years ago. The excavations in Nagórzyce were created as a result of the exploitation of sand necessary for the production of glass, thanks to which chambers, niches and corridors resembling natural caves were created. Thanks to the funds from the European Union, the former caves were adapted for an underground tourist route. The underground tourist route Groty Nagórzyckie in Tomaszów Mazowiecki is the first facility of this type in central Poland.