The Treaty of the Pyrenees which settled the border between France and Spain in 1659 caught several villages 'on the wrong side' and the deal was that they would simply change nationality (life was so simple before democracy).

However the town of Llivia, the former Roman oppidum of Julia Libica (population currently about 1600 but technically a city at the time of the Treaty due to its former status of capital of Cerdanya) retained its Spanish nationality and now exists as an exclave of Spain (being a part of the Spanish province of Girona) 2km inside France on the southern slope of the Pyrenees.

Everything in Llivia is exactly as it would be if it were still on the Spanish side of the border. The language is Catalan (there are those for whom Catalunya is not a part of Spain, hence the graffiti saying ¡Catalunya no es Espana!'). Shops are apert or tancat, open or closed, today is dimarts, Tuesday, and tomorrow will be dimecres.

There is no visible border, but dotted around the town are 45 boundary stones marked LL on the Spanish side and marked with the initials of the relevant French village on the 'outside'. I'll get some photos before I leave.