10 Euros European Union Membership of Portugal and Spain

Issued on the twentieth anniversary of Portugal and Spain's accession to the European Communities on 1 January 1986, this coin marks what was then the single largest expansion of the bloc since its founding — bringing two Iberian nations that had only recently emerged from decades of authoritarian rule under Franco and Salazar into the democratic fold of European integration. Spain's accession negotiations had been particularly protracted, stretching over nearly a decade due to French agricultural lobbying against Iberian competition in wine, fruit, and olive oil markets.

The .500 fineness is characteristic of Portuguese commemorative silver from this period, a deliberate cost-control measure adopted by INCM.