France–Spain border

The France–Spain border was formally defined in 1659. It separates the two countries from Hendaye and Irun in the west, running through the Pyrenees to Cerbère and Portbou on the Mediterranean Sea. It runs roughly along the drainage divide defined by the Pyrenees, though with several exceptions.
The Franco-Spanish border runs for 656.3 kilometres (407.8 mi) between southwestern France and northeastern Spain. It begins in the west on the Bay of Biscay at the French city of Hendaye and the Spanish city of Irun (43°22′32″N 01°47′31″W﻿ / ﻿43.37556°N 1.79194°W﻿ / 43.37556; -1.79194). The border continues eastward along the Pyrenees to the sovereign nation of Andorra (42°36′13″N 1°26′30″E﻿ / ﻿42.60361°N 1.44167°E﻿ / 42.60361; 1.44167). At this point, the small country interrupts the border between Spain and France for 63.7 kilometres (39.6 mi) on the Spanish side and 56 kilometres (35 mi) on the French side. Then the border continues eastward (42°30′09″N 01°43′34″E﻿ / ﻿42.50250°N 1.72611°E﻿ / 42.50250; 1.72611) to the Mediterranean Sea at Cerbère in France and Portbou in Spain (42°26′09″N 03°10′26″E﻿ / ﻿42.43583°N 3.17389°E﻿ / 42.43583; 3.17389).
From west to east, crossing the border:
Spain has an exclave in France, Llívia, in the Pyrénées-Orientales.
Near the western end of the border, following the course of the river Bidasoa, Pheasant Island (located in the middle of the river) has an unusual border regime: the island is a condominium whose sovereignty is shared between the two countries: one country in January–June each year, and the other country in July–December.
The formal layout of the Franco-Spanish border dates back to the signing of the Treaty of the Pyrenees between the kingdoms of Spain and France in 1659. This was followed by the Treaty of Llivia the following year, which transferred to France the sovereignty of several villages in the valley of Querol.
Later there were some further agreements covering specific areas:
The final definition, which for the most part is still in force, is set out in the Bayonne Treaties between 1856 and 1868. During the mandates of Queen Isabel II and the French emperor Napoleon III ,several agreements were signed between the two countries by which the border was established:
Later both countries concluded agreements under the same point. In 1980 an agreement was signed to define the border into the Bielsa-Aragnouet tunnel, and 1984, during the construction of the road linking the Roncal Valley with Arette, a mutual transfer of land of 2710 m (29,170 sq ft) was agreed.
In 1995, with the entry into force of the Schengen Agreement, border controls for people and goods were abolished, thus ensuring freedom of movement across the border.
Following the provisions of the treaties of Bayonne, the border is physically marked on the ground by 602 cairns showing the division between the two countries. These markers are numbered from west to east: the first located on the Bidasoa and the last in Cap Cerbère, marked with consecutive numbers and letters.
Another 45 cairns mark the border around Llivia; they are numbered anticlockwise from the number 1 at the entrance of the French road RD-68 into the enclave. Maintaining this signaling runs either on behalf of both states.