Do you need a passport to travel to Barcelona
Yes, a passport is required.
Yes, you would need a passport for this as you are traveling internationally.
its natural u ned visa to travel from one country to another
That would depend on where you originate from. From North America you would need a passport. From a country in the European Union, of which Denmark is a part, you would not need a passport.
You need a passport to travel anywhere out of the country you where born in.
To leave the United States you would need a passport. This is also required for air travel, and land travel.
Yes you would need a passport. You would also need a visa.
Whether international travel or not the answer would be no. You would however need your passport at customs.
Yes, you need a passport to travel to Europe.
Yes, you need a passport to travel to Paris.
You need a passport