In the middle of the Bidasoa River, between the Spanish town of Irún and the French city of Hendaye, lies Pheasant Island, a patch of land just 6,820 square meters in size. Despite its modest footprint and lack of inhabitants, the island is the setting for one of Europe’s most unusual border arrangements: France and Spain jointly hold it, while responsibility for its administration alternates between them.
From February 1 to July 31, Spanish authorities administer the island. On August 1, French authorities take over until the end of January. The handover is marked by a formal ceremony attended by civil and military officials from both countries. Flags are exchanged and the transfer of administrative responsibility is recorded, but the island does not become French or Spanish in turn: its ownership remains joint and undivided throughout the year.
Historic Agreements
The arrangement’s legal foundation is the Treaty of Bayonne, signed on December 2, 1856. Article 27 states that the island “shall belong jointly and undivided to France and Spain,” establishing shared ownership rather than assigning it exclusively to either country. A later agreement in 1901 set the current system of alternating six-month periods of administration. The rules also clarify which courts have jurisdiction in legal cases: Spanish and French citizens answer to their own national authorities, while citizens of other countries fall under the jurisdiction of whichever nation is in charge at the time.
A Site of Peace
Pheasant Island’s diplomatic significance dates back further still. On November 7, 1659, it hosted the signing of the Treaty of the Pyrenees, which ended nearly 25 years of conflict between the French and Spanish crowns. The negotiations were led by Cardinal Mazarin for France and Don Luis de Haro for Spain. Situated in the river between the two realms, the island served as a neutral meeting place. The treaty included major territorial changes, including the transfer of Roussillon and parts of Artois to France, and arranged the marriage of Louis XIV of France to Maria Theresa, daughter of Philip IV of Spain. The union was celebrated in San Juan de Luz the following year.
Today, the island’s only structure is a mid-19th-century monument commemorating the historic treaty and recalling the island’s role in European diplomacy.
Governance and Daily Reality
Responsibility for the island alternates between the naval commanders of San Sebastián and Bayonne, who act as official representatives of their respective countries. The municipalities of Irún and Hendaye assist with maintenance and conservation, but there are no homes or permanent residents, and the island has no local government. Trees and wild vegetation surround the solitary monument, a reminder of cooperation between the two countries.
Pheasant Island remains closed to the public, with access restricted to official visits and ceremonies. Its status as the world’s smallest condominium and its peaceful, ritualized transfer of administrative authority make it a rare example of enduring cross-border collaboration.
Pheasant Island is also a reminder of how historical rivalries can give way to practical cooperation. Though uninhabited and largely inaccessible, its continued existence as shared territory shows how neighboring countries can manage borders without conflict, a lesson that remains relevant in today’s Europe.
