In the commune of Rogny-les-Sept-Écluses in the Yonne department, a unique staircase of seven locks was built in the 17th century to address a 24-meter elevation difference between the Loire and Seine rivers. These locks were part of the Briare canal, one of France’s oldest canals and the first of its kind to use a "water divide" system, allowing water to be transferred between different levels to enable boat passage. The project was initiated by King Henri IV and his advisor, Maximilien de Béthune, known as Sully, as early as 1597. The goal was to link the Mediterranean Sea to the Atlantic Ocean and the English Channel through an extensive network of canals. The locks were designed by engineer Hugues Cosnier, who was inspired by the engineering concepts of Leonardo da Vinci. Construction began in 1604 and involved 12,000 workers, many of whom were protected by 6,000 soldiers. The site was challenging to build on, as it was marshy and surrounded by numerous ponds. These ponds were dug by hand over several years to make the terrain suitable for the canal. The Briare canal officially opened for navigation in 1642, marking a significant achievement in early European engineering. However, the original staircase had a design flaw that prevented boats from passing through the joined locks. This issue was resolved in the late 19th century with the introduction of the Freycinet standard, a set of modern engineering principles that improved canal efficiency. As a result, a new route with six separate, spaced locks was built, better suited for modern navigation. The original staircase was then abandoned, and its stone locks have not carried water since the end of the 19th century. Today, the historical staircase remains dry and unused, as no boats have passed through it since its decommissioning. Classified as a historical monument, the site has become a popular tourist attraction. Each summer, it hosts a pyromusical show, drawing more than 10,000 visitors. Meanwhile, the Briare canal continues to function a short distance away along the Freycinet route, still used by pleasure boats for leisurely cruises.