From time immemorial and at least since Roman times, Sisteron has been considered a strategic point, with its rocky outcrop overlooking the valley which opens the passage between Provence and Dauphiné. Throughout the ages men have devised plans, built and fortified the walls of the city. "It is the most powerful fortress of my kingdom" said Henri IV of the Citadel of Sisteron. But of the fortifications of the Middle Ages, there now remains only a keep, a walkway from the 12th century, and ramparts from the 14th century. In 1692, Vauban undertook plans to modernize and strengthen the fortress which would give it its current silhouette. In the middle of the 19th century, an impressive underground staircase was dug into the rock to connect it to the city. Damaged by bombing in 1944, the fortress was again restored in the 20th century. Thus, the citadel dominating Sisteron, which we can currently admire, is the result of a set of works from very different periods, and the substrate of more than eight centuries of architecture and history.
Opposite the citadel, on the other bank of the Durance, stands the rock of La Baume, made up of vertical strata and folds of limestone. Passing through a cave in the rock, it is possible to reach the top of the mountain on foot. The site is also conducive to the practice of via ferrata with walls spaced about ten meters apart. The mountain of La Baume is also pierced by a tunnel which allows the A51 motorway to cross it from side to side. You won't necessarily see it on your bike, but you will notice it if you drive around.