The Latin obsession with spatial limits goes right back to the legend of the foundation of Rome: Romulus draws a boundary line and kills his brother for failing to respect it. If boundaries are not recognized, then there can be no civitas. Horatius becomes a hero because he manages to hold the enemy on the border - a bridge thrown up between the Romans and the Others. Bridges are sacrilegious because they span the sulcus, the moat of water delineating the city boundaries: for this reason, they may be built only under the close, ritual control of the Pontifex. The ideology of the Pax Romana and Caesar Augustus's political design are based on a precise definition of boundaries: the force of the empire is in knowing on which borderline, between which limen or threshold, the defensive line should be set up. If the time ever comes when there is no longer a clear definition of boundaries, and the barbarians (nomads who have abandoned their original territory and who move about on any territory as if it were their own, ready to abandon that too) succeed in imposing their nomadic view, then Rome will be finished and the capital of the empire could just as well be somewhere else.

Eco, U. (1992). Interpretation and Overinterpretation. Cambridge and New York: Cambridge University Press, pp 27-8.

Borders in Europe have been negotiated on countless occasions in the course of time, leaving us with a body of collectively negotiated agreements that represent attempts to stabilize flexible, unstable and controversial borders between ruling classes, kinships, peoples and states. Throughout history, people have organized themselves into groups in order to optimize the realization of their common interests, as the Swedish social scientist Sven Taegil has argued. The politically negotiated borders of states have been marked and re-marked in the terrain, and also in peoples' minds. From the 15th to the 21st century peace treaties have been signed by local, regional and national negotiators after wars or non-violent actions. Probably the most famous politically negotiated European treaties are the Peace of Augsburg (1555), the Westphalian Peace Treaty (1648), the Congress of Vienna (1815), the Treaty of Versailles (1919) and the Congress of Potsdam (1945), a list to which we could add the non-violent Treaty of the European Union (1992).

Katajala, K., & Lähteenmäki, M. (2012). 'Foreward'. In Katajala, K., & Lähteenmäki, M. (eds) Imagined, Negotiated, Remembered: Constructing European Borders and Borderlands. Berlin: Lit., pp 7-14, p. 8.

The borders of the EU are nowadays often seen rather stereotypically as simply becoming lower inside the Union and stronger around its outside. The Union's area is more complex, however, and such features as the Schengen zone make a major difference. The situation of the EU and its internal and external borders serve to characterize more broadly the key issue related to borders: their selective openness.

Paasi, A. (2011) 'A Border Theory: An Unattainable Dream of a Realistic Aim for Border Scholars?'. In Wastl-Walter, D. (ed.) The Ashgate Research Companion to Border Studies. Farnham: Ashgate, pp 11-31, p. 12.