Rijkholt is a small village in the Netherlands on the east bank of the River Maas, south of Maastricht. In 1881 neolithic flint mines were discovered in the chalk geology to the east of the village. The extraction took place across 12 hectares and the area where prehistoric knapping remains have been found is around 25 hectares.
Surface excavations here were conducted over the years but in the 1960s they continued in a novel manner. Between 1964 and 1972 mining engineers from the former Dutch coal mines drove an east-west tunnel 150 metres straight into the hillside, intersecting and giving access to a number of mine galleries and 80 shafts, sampling a mined area up to 20 metres wide.
The excavation yielded an extrordinary 14,500 artefacts, mainly mining tools. Carbon dating showed the mine operated around 4,000 BC and perhaps continued in use for 1,000 years. Surface remains can be visited at any time and tours of the underground passage are also sometimes arranged.
The site is comparable with the better known (and World Heritage Sites) at Spiennes in Belgium and Krzemionki in Poland. The UK has Grimes Graves which is also open to visit.