Timeline

Heritage classified

Key figures

Origin and history

The lock of Ognon is a major hydraulic structure of the Canal du Midi, located in Olonzac, Herault. Designed as a double chamber lock, it is framed by the Pechlaurier lock in the east (2,726 m) and the Homps lock in the west (689 m). Its architecture reflects the civil engineering techniques of the 17th to 19th centuries, with an aqueduct bridge crossing the Ognon River, spanners and a defence door integrated into the system.

The construction of the lock began around 1693, according to the plans of architect Emmanuel de Lestang, also known for having designed the canal bridge of the Repudre, the oldest in Europe on the Canal du Midi. A reconstruction project was planned in 1833, marking a technical development or a response to growing navigation needs. These developments are part of the wider history of the Canal du Midi, classified as a UNESCO World Heritage Site for its role in pre-industrial river transport.

The complex — double locks, aqueduct bridge, defence gate and spanners — was listed as historic monuments in 1998. This protection recognizes its heritage value, both for its engineering and for its integration into the Languedoc landscape. The locks of Ognon thus illustrate the hydraulic control of past centuries, while at the same time showing the successive adaptations of the canal to economic and technical requirements.

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