Krzemionki

Krzemionki, also Krzemionki Opatowskie, is a Neolithic and early Bronze Age complex of flint mines for the extraction of Upper Jurassic (Oxfordian) banded flints located about eight kilometers north-east of the Polish city of Ostrowiec Świętokrzyski. It is one of the largest known complex of prehistoric flint mines in Europe together with Grimes Graves in England and Spiennes in Belgium.

• http://en.wikipedia.org/wiki/Krzemionki