Helsinki has a lot of diversity between districts. There's the working people's Kallio, the rich people's Eira, the prestigiuos Töölö, the old Kruunuhaka, the classical Katajanokka and the über cool Punavuori and of course the center.

Center

In Helsinki downtown is just called the center. It's filled with shops and department stores and also office buildings. It has significant cathedrals and squares. Don't forget the summery Kauppatori, which sells gorgeous strawberries, peas and ice-cream. Don't forget the Santa, who visits the main street, Aleksanterinkatu, every Christmas.

Töölö

Töölö has wonderful old residential buildings representing art deco for example. Try the cafés on Museokatu or go to the small market square called Töölöntori further. There you can buy fresh products or sit at an outside-café.

Kruununhaka

Kruununhaka is an old, old district. It's filled with antique and design shops.

Kallio

Area roughly between Hakaniemi and Sörnäinen. Used to house the lower income residents, with most young Residents of Helsinki living in Kallio at one time or another. Has become one of the coolest places to visit. 

Islands

Helsinki is surrounded by the sea on three sides, and the numerous small islands close by make the city very attractive when approached by boat.  Visit e.g. Korkeasaari, the Zoo island, Seurasaari Open Air museum island, Suomenlinna Fortress Island, or the many smaller ones, some with a nice summer restaurant. You can take a ferry to some of the islands from the Market Place, or try the 2-hour Helsinki by sea sight-seeing.

Helsinki metropolitan area

Helsinki together with two neighboring cities, Espoo and Vantaa, are considered the Helsinki metropolitan area. Vantaa is North of Helsinki, and the Helsinki International Airport is located in Vantaa, some 35 min. drive from Helsinki centre. Espoo is more of a residential area with also lovely country-side setting e.g. in Nuuksio national park.