Le patrimoine souterrain de Pontoise

Useful Information

Location: Meet at the Office de Tourisme de Cergy-Pontoise.
Open: During School Holidays Sun 14:30.
22-OCT-2014, 18-FEB-2015, 22-APR-2015, 08-JUL-2015, 15-JUL-2015, 05-AUG-2015, 12-AUG-2015 14:30.
Fee: Adults EUR 6.50, Children (7-14) EUR 4.50, Children (0-6) free.
Classification: SubterraneaRock Mine SubterraneaCellar SubterraneaCave Church
Light: LightIncandescent Electric Light System
Guided tours: D=1h
Photography: Allowed
Bibliography: Georges Duclos (1968): Pontoise féodal et souterrain, Pontoise, Imprimerie Pâris, 1968, 237 p.
Jean-Luc Maire (1990): Aperçu géologique du site de Pontoise et méthodes d'exploitation du calcaire, in Clan spéléo pontoisien, La cave des Moineaux à Pontoise, Pontoise, EDF-GDF Services, 1990, non paginé.
Georges Duclos (1944): Les souterrains de l'ancien couvent des Cordeliers de Pontoise, COMM S&O, LIe volume, 1943-1944, 40-45.
Address: Office de Tourisme de Cergy-Pontoise, Place de la Piscine, 95300 Pontoise, Tel: +33-134-417060, Fax: +33-134-417068. E-mail: contact
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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The city Pontoise, not far from Paris, is located in the middle of the Paris Basin, which is full of sedimentary rock. Right below the surface is a massive layer of Campanian (Cretaceous) limestone. This limestone was used to build houses, and for this reason it was quarried. The best layers were located below ground, and so the quarries were underground, following the mined rock. Over many years, between the 12th and 17th century, a lot of underground structures were created. The floor below the historic city core is virtually riddled with caves. Some of those caves were later used as cellars, others for living, some even for worshipping.

There are numerous sites underground, all of them are open to the public. On the European Heritage days, one weekend in September, all of them are opened for two days. The rest of the year there are guided tours by the Tourist Office, which show a few of them.