Complex sentence: Ympyrätalo was designed by architects Heikki and Kaija Siren and opened in 1968, originally serving as offices for Kansallis-Osake-Pankki.
Split into simpler sentences: Ympyrätalo was designed by architects Heikki and Kaija Siren and opened in 1968. It originally serving as offices for Kansallis-Osake-Pankki.