At the northern end of the longest continuous street axis in Helsinki, formed by Unioninkatu and Siltasaarenkatu, is the Kallio Church. The church is one of the principal works of Lars Sonck, a master of Art Nouveau. Located on a high hill at the intersection of various major streets, the church is the focal point of the Kallio district. Its tower rises 94 meters above sea level, which makes it one of the most impressive landmarks in the city.

Sonck was commissioned to design the church in 1906 thanks to his winning competition entry. At this time Finnish architecture was beginning to break away from the national-romantic and versatile Art Nouveau style towards a more rationalist approach. This transition is apparent in the Kallio Church, which is completely symmetrical and plainly geometric. Its elevations are clad in grey granite slabs of varying coarseness, which, however, is a common feature of national-romantic Art Nouveau.

During the extended design phase, Sonck experimented with numerous options for the top of the monumental tower. The seven bells in the tower play a choral composed for the church in 1911 by Jean Sibelius.