Finland's architecture museum occupies a neo-Rennaissance building dating from 1899. Exhibitions are its key focus, including the fascinating Decades of Finnish Architecture 1900–1970, which runs until the end of 2020 and covers National Romanticism, classicism, functionalism and modernism, laying the groundwork for Finland's definitive 1970s works, as well as shorter retrospectives and thematic exhibitions. Permanent displays include architectural models, drawings and photographs. There's a library and an excellent bookshop.
The combination ticket with Helsinki's Design Museum is fantastic value.
In summer, there's also a shared summer pavilion between the two museums, built by students from collaborating universities to create a sustainable structure, with free admission.
Another summer highlight is the guided walking tours in English run by the architecture museum in July and August. At 10am from Thursday to Monday, two-hour tours of Helsinki (adult/child €10/5), start from Senaatintori and finish at Helsinki's 1919-built National Romantic (art nouveau) train station.
In the beautiful park Kaivopuisto, the museum also has a wooden villa, which opens for events; check for updates.