European Union: EU is a political and economic union that comprises 27  states members. EU Citizenship is afforded to all citizens of member states, in addition to national citizenship. giving them rights, freedoms, and legal protections available under EU law. EU citizens have freedom of movement and the freedom of settlement and employment across the EU.

EU members have the right to consular protection by embassies of other EU member states if their country is not represented by an embassy or consulate in the foreign country in which they require protection or other types of assistance.

Currency: 

The euro is the currency of only 19 of the EU member states: Austria, Belgium, Cyprus, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Portugal, Slovakia, Slovenia, and Spain. The rest of the countries have their currency.

Connexion: The Internet is very fast, and all countries are on 5G. Wi-Fi connection everywhere you go, free or on demand. If you are from the EU, roaming is free of charge. You can call and connect to your mobile data as if you were in your country of origin without extra costs.

Railroads: You will have connexions through all the countries, easily accessible, not very expensive in most countries, and very expensive in France, especially during peak season.