Katajanokka is a neighbourhood of Helsinki, Finland, with around 4000 inhabitants in 2005. The district is located adjacent to the immediate downtown area, though in the first major town plan for Helsinki from the mid-18th century, the area fell outside the fortifications planned to encircle the city.

Helsinki is the capital and most populous city in Finland. It is located on the shore of the Gulf of Finland and serves as the seat of the Uusimaa region in southern Finland. Approximately 675,000 people live in the municipality, with 1.25 million in the capital region, and 1.58 million in the metropolitan area. As the most populous urban area in Finland, it is the country's most significant centre for politics, education, finance, culture, and research. Helsinki is situated 80 kilometres (50 mi) to the north of Tallinn, Estonia, 360 kilometres (220 mi) to the north of Riga, Latvia, 400 kilometres (250 mi) to the east of Stockholm, Sweden, and 300 kilometres (190 mi) to the west of Saint Petersburg, Russia. Helsinki has significant historical connections with these four cities.