Malpasset Dam

Malpasset Dam is a ruined structure in the Reyran river valley near Fréjus, France, with massive concrete pieces scattered across the landscape. The remains display the curved arch design that once rose 70 meters high and stretched 220 meters across the valley.

Construction began in 1952 under engineer André Coyne and was completed in 1954, introducing a revolutionary concept of thin curved walls. On December 2, 1959, the dam collapsed following heavy rains, triggering a catastrophic flood.

The name comes from a Provençal term meaning dangerous passage, referring to the steep terrain that was already difficult before construction. Visitors today walk among the concrete remains and see the curved form that once held back water.

The site sits in the Reyran river valley and is accessible on foot during dry conditions, with sturdy footwear recommended. The Fréjus tourism office organizes guided walks that explain the history and visible remains.

Some concrete blocks weighing over 600 tons were carried by the flood wave all the way to the sea, demonstrating the immense power of the water. A geological fault beneath the foundation that went undetected during construction is considered the primary cause of the collapse.