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What does the decommissioned Hanasaari Power Plant look like inside? How about Aalto University’s Acoustics Lab – or a home built inside a former prison service building?
Open House Helsinki is once again opening the doors to buildings and spaces that are normally off limits to the public. The free architecture festival takes place from 3 to 6 September 2026.
This year’s programme features almost 50 locations and more than 60 tours, events and open-house sessions. For the first time, the festival is expanding beyond Helsinki into neighbouring Espoo.
Power plants, private homes and hidden interiors
The biggest draws are the places whose doors usually remain firmly closed. Highlights include the decommissioned Hanasaari coal-fired power plant, Parliament House and Kalervo Kallio’s studio building in Munkkiniemi, which now provides workspaces for visual artists and musicians.
One of the most intriguing locations can be found in Katajanokka. A service building belonging to the former prison, originally constructed in the 1890s, has been converted into five two-storey homes. Visitors can explore Asunto Oy Helsingin Linnanpuisto from noon to 3pm on Thursday 3 and Friday 4 September, with no advance booking required. Only 20 to 30 visitors can enter at a time.
Many of the most sought-after tours, including those of Hanasaari Power Plant and Parliament House, are fully booked at the time of writing. It is still worth checking the festival website, however, as places may become available through cancellations.
Alvar Aalto’s studio becomes an open-air cinema
The programme is not confined to building interiors. There are also outdoor architecture walks around Jätkäsaari, Etu-Töölö, Eastern Pasila and Siltavuori, as well as the Suvilahti and Crown Bridges area. Those interested in landscape architecture can explore new and recently renovated green spaces in Jätkäsaari, Kuninkaantammi and Pitäjänmäki.
One of the weekend’s most atmospheric events is an open-air film screening in the garden of Alvar Aalto’s studio. Its amphitheatre-like seating and the white wall opposite create an almost impossibly perfect outdoor cinema. Admission to the screening on Saturday 5 September is free, although access to the garden may be restricted if it becomes too crowded.
The theme for 2026 is architectural competitions, marking 150 years of the tradition in Finland. Around half of the festival’s locations were created as the result of design competitions. They include Helsinki Central Station, Oodi Central Library, Finlandia Hall and the new Aurinkokello Comprehensive School and Daycare Centre in Pasila.
The main Open House Helsinki programme is free. Some tours require advance registration, while visitors can simply turn up at the open-house locations. Additional events organised by festival partners may charge admission.
Open House Helsinki
3–6 September 2026
Various locations across Helsinki and Espoo
Free admission to the main festival programme
See the full programme and registration details