The term 'Northern Capital' refers to the four major cities located in the northern hemisphere. Reykjavik, the capital of Iceland, is a nine-letter word. Oslo, the capital of Norway, is a four-letter word. Ottawa, the capital of Canada, is a six-letter word. Riga, the capital of Latvia, is a four-letter word. These four cities are all considered to be important political and economic centers in their respective countries, and are often referred to as the 'Northern Capitals'.