[3] In 1971, he founded the International Library (Διεθνής Βιβλιοθήκη), which quickly became the gathering place for the Athenian anarchist and anti-authoritarian movement.

[6] He played a central role during the Athens Polytechnic uprising, particularly by facilitating the publication of leaflets and materials for the movement.

[7] He participated in and encouraged the central action of the uprising by occupying the Faculty of Athens with his group on 14 November 1973,[3][5] and strongly supported the idea that the occupation should be sustained over time, which was ultimately adopted.

occupied the entrance of the Athens Polytechnic during the first days of the occupation, until communist militants removed it[4] and the tanks of the dictatorship forcibly entered the university grounds.

[1] He was arrested and then acquitted for allegedly attacking the police outside the courthouse where Rolf Pohle, a member of the Red Army Faction (RAF), was having his extradition to Germany granted by the Greek state.

[2] Konstantinidis is one of the prominent figures in the Greek anarchist movement of the late 20th century; he is frequently mentioned in testimonies regarding these circles.