situation, the weather and the excursion funds available to school groups. In 2019 a total of 423,229 people visited Heureka, thanks to the popular Giant Dinosaurs exhibition. Because of the lock-down caused by the COVID-19 pandemic, the number of visitors in 2020 was only 165,428. Heureka's most active year was its inaugural year 1989, when 431,244 people visited the science centre in a bit over eight months. In terms of number of visitors, Heureka is one of the most popular for-pay attractions in Finland, and it has been the most popular museum in Finland on many years. When the science centre was originally being planned in the 1980s, it was estimated to attract 250,000 people per year. The long-time average has risen slightly higher than this estimate, to about 280,000 visitors per year. The number of visitors varies considerably each year because of the services offered and the economic situation of Heureka and its competitors, which affects the demand for various visitor groups and consumption decisions. Building In addition to the exhibition spaces, the building consists of an auditorium, meeting rooms, a planetarium, a restaurant and a shop. The facade of the building facing the railway track makes use of mirror glass, intended to shield the building from the noise caused by the trains. The structures in the facade are phased into 31 parts of a whole of a hundred metres of length, with the corresponding spectral colours based on a laboratory analysis and special paints made based on it. The coating of the outer walls of the pillar hall uses pretensed white concrete slabs one inch thick. The shell elements have been sandblasted on their surface and are 60 × 120 cm in area. The central inner space and architectural focus point of the science centre is its 14-metre-tall cylindrical exhibition hall. The pillar module of the main exhibition space is 9.6 metres in both height and width. Its pillars consist of sub-pillars, with four in the central area, two on each edge and one in each corner. This structure is intended to visualise the relative distribution of load. The main exhibition space is surrounded by the pillar hall and an arc hall supported by laminated beam arcs. The sphere of the planetarium and the sector-shaped auditorium intersect and enter into the modular pillar hall, and partly into each other. Each part of the building is fitted with a