This paper is a paraphrased summary of the book published in Finnish on the 100th anniversary of the Sodankylä Geophysical Observatory in 2013 (edited by Heikki Nevanlinna, 2017). The history of the Geophysical Observatory in Sodankylä (SGO) is described by the personalities who have run it and have shaped the observatory. Thereafter, we describe the history from a technical point of view, i.e., what the measurements were and which instruments were primarily used at the observatory.