Strictly for the lover of arcane points of international law and history...

You are not allowed to visit Pheasant Island, which lies near the Atlantic Ocean terminus of the French-Spanish border. But “it can easily be seen from the Joncaux bank, on the Bay Path,” the Web site for the local tourist office [1] suggests, without a hint of irony.

For border enthusiasts, that feels like insult added to injury. They’re condemned to contemplate the tiny eyot [2] from either bank of the Bidasoa, the border river that separates Hendaye in France from Irún in Spain [3]. And they can only wonder about the inscription on the gleaming white monolith that graces the island.

That monument commemorates the Treaty of the Pyrenees, concluded on the island in 1659. It fixed the Franco-Spanish border, following the mountain chain of that name as the natural boundary between the two countries [4]. But tiny Pheasant Island is more than the place where that treaty was signed.

For centuries, the island, less than an acre in size, was a favorite royal meeting place, often serving as a bridal exchange. In 1615, Louis XIII of France and Philip IV of Spain first met their wives — each other’s sisters — on the island, after having married them by proxy [5]. Later that century, Pheasant Island would be the place where both Louis XIV of France and Charles II of Spain first laid eyes on their respective brides.

In recognition of its historical significance, Pheasant Island [6] is also known in French as Île de la Conférence [7]. The Treaty of 1659 consecrated its significance to both countries by establishing it as a rare example of that curious border arrangement: a condominium.

A condominium is a territory jointly administered by two or more countries, often (but not necessarily) a territory on the common border between the parties involved. As one might surmise, such an arrangement depends on the benevolent cooperation of all parties involved — and indeed, historically, most condominiums have not survived very long.

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