France–Switzerland border

Burgundy, Savoy and single buildings

The line mostly follows the historic limits of Burgundy and Savoy against the Bishopric of Basel and the lands of Neuchâtel, Vaud, Geneva and Valais. The Treaty of Paris of 1814 recognised the newly neutral Swiss Confederation with roughly today’s borders, and agreements up to 1824 completed it. In 1862 the strategic route through the Vallée des Dappes, long a source of irritation, went to France in exchange for a like area just to the north.^[1]

Conventions of 1953 made fourteen tiny adjustments in the north to end shared control of paths and put buildings wholly in one country: all the buildings at Queue au Loup went to Switzerland, as did a building at Le Paradis and another that the line had cut in two. In Lake Geneva a median line was replaced by straight segments.^[1]

Colliders under the line

CERN’s Large Hadron Collider, which started up on 10 September 2008, is a 27 km ring of superconducting magnets in a tunnel 100 metres underground on the Franco-Swiss border near Geneva.^[2] Its planned successor, the Future Circular Collider, would be a ring of about 90 km under France, Switzerland and even Lake Geneva, costing about CHF15 billion; CERN’s Council endorsed it as its preferred next project on 22 May 2026, with a final decision expected in 2028. Its excavation and power demands have raised environmental concerns.^[3]