A small exhibition hall on Pohjoisesplanadi, in a 1906 building by Lars Sonck originally designed as a bank. The interior is one of the city's best preserved art-nouveau (Jugend) interiors — granite columns, ornamental ironwork, a barrel-vaulted ceiling. The hall now hosts small exhibitions on Helsinki history and design, and is free to enter.
A 15-minute stop — pop in to see the room itself even if the exhibition is not your subject — and conveniently placed on a walk between Senate Square and the Esplanadi park.