The story
On 18 January 1993, Henri Grenet, president of the Bayonne-Anglet-Biarritz District, and Eli Galdos, deputy general of the Gipuzkoa Provincial Council, signed a cross-border cooperation agreement that would be the germ of the Basque Eurocity.
In 1997 the Bayonne-San Sebastián cross-border observatory was created by the Provincial Council of Gipuzkoa and the Bayonne-Anglet-Biarritz District (converted into the Bayonne-Anglet-Biarritz agglomeration community), under the legal form of an Association European Economic Interest.
In 2001, the Bidasoa-Txingudi Consortium, which brought together the municipalities of Irun, Hondarribia and Hendaye, joined the Eurocity.
From Wikipedia’s article on Basque Eurocity Bayonne-San Sebastián, shared under CC BY-SA 4.0.3