Heikki Siren was born on 5 October 1918 in Helsinki, only a few months after the Civil War. He was the son of architect J.S. Sirén and Sirkka Sirén (née Syrjänen). Heikki Siren studied architecture at the Helsinki Technical University, his father as a teacher. After receiving a diploma of architecture in 1946, he worked at his father’s private office.
Katri Anna-Maija Helena Tuominen was born on 23 October in Kotka. Kaija Tuominen studied architecture at the Helsinki Technical University and received her diploma of architecture in 1948. She married architect Heikki Siren, took the name Kaija Siren and in 1949 she established a shared office with her husband, Kaija and Heikki Siren Architects. The Siren’s are known as one of the leading Finnish modernists. One of the Sirens’ four children, Jukka Siren is an architect and has continued the work of the office.
Kaija Siren died at the age of 80, on 15 January 2001. Heikki Siren died at the age of 94, on 25 February 2013.