To avoid a certain dissonance the formula “in Avignon” is increasingly used both by the media and by the street. It is, however, incorrect when it applies to the city, that is to say, to the boundaries of the commune. However, historically and for centuries it has been appropriate for both Avignon and Arles. So we went to Arles or Avignon as we go today in Provence or in France. In fact, the preposition “en” designates a country, a place: Arles was a kingdom in the Middle Ages until 1483, when it joined the kingdom of France, Avignon, bought from Queen Jeanne (of Naples and Countess of Provence) In 1348 by the Holy See was a territory much larger than the present intramural space and gathered spaces that today are full-fledged communes and formed with the Comtat Venaissin (sold by Philip the Bold to Pope Gregory X in 1274) two real states striking currency and flying the flag until 1791, date of their attachment to France. On the other hand, the influence of the Provencal language is also decisive: “vau à-n-Arles, vau à-n- Avignoun: I go to Arles, I go to Avignon” (A before a vowel takes a n Euphonic to prevent elision); In other cases this euphony can be constructed with other consonants like “vau à-z-Aix: I go to Aix, vau a-z-Apt, I go to Apt”. In addition, Frédéric Mistral by giving back to the Provençal its place of full language translated by: vau-à-n’Avignoun, vau-à-n-Arles by I go in Avignon …. In Arles and has, by this translation which is in fact only the reflection of the political ambiguity of its author put a little more confusion. Today, it is customary to accept expressions in Arles or Avignon to designate the region around each of these cities, but it is certain that when one goes to the city of Arles or Avignon one goes In Arles, in Avignon.