“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.

Pheasant Island is not only the oldest surviving condominium, it is also the only one where sovereignty isn’t shared simultaneously, but alternately. For six months a year, Pheasant Island is French; for the other six, it is Spanish.” Frank Jacobs, NYT Opinionator