Oslo is the capital city of Norway and is located in Northern Europe. It has a population of over 658, 000 people and is the most populous city in the country. Madrid is the capital of Spain and is located in the south-central part of the country. It is the third-largest city in the European Union with a population of over 3.2 million people. ATHENS is the capital of Greece and is located in the southern part of the country. It is one of the oldest cities in the world and has a population of over 3.2 million people.