Seuil de Naurouze
The Seuil de Naurouze, aka Col de Naurouze, is a mountain pass in southern France. It is the watershed point identified by Pierre-Paul Riquet when he designed and built the Canal du Midi. Water falling on the western side of this point flows to the Atlantic Ocean and on the eastern side to the Mediterranean Sea. It is on the border of the department of Haute-Garonne and the department of the Aude. 
In 1827, the heirs of Riquet built the Riquet Obelisk. The obelisk has a dedication: "To Pierre-Paul Riquet, Baron Bonrepos, author of the Two Seas Canal in Languedoc". It is erected near the site of the former octagonal holding tank, called the Bassin de Naurouze created during the building of the Canal du Midi.
- Rolt, L. T. C. (1973). From Sea to Sea. Ohio University Press. ISBN 9780713904710.
- Mukerji, Chandra (2009). Impossible Engineering: Technology and Territoriality on the Canal du Midi. Princeton University Press. ISBN 978-0-691-14032-2.
- Kiessler, Bernd-Wilfried (2009). The Canal du Midi A Cruiser's Guide. Adlard Coles Nautical. pp. 115–116. ISBN 978-1-4081-1273-1.