Radical modernism of the20th-century posed demands for bridging art with design and production, for the rejectionof the illusory space of the image, for the various activities of body presence in the city's space and for collectivity. The goal of the above was to establish new foundations in the relationship of arts with architecture, interms of political and social reorganization.

Today, at a time of civilian fragmentation and homogenization,but also in a period of crisis in the relationship between place and subject, both the architecture of art and the art of architecture, share common goals forreflectingupon the public sphere and for redesigning it. Architecture not only provides built-in frames, but it also highlights scenarios of organizing behaviors and lifestyles. At the same time, artfurther than providing aesthetic valuesit also attempts to re-establish the space and activate the public through interactive processes and livedexperiences.

The main focus of this research is the study of groups of people that have acted or still act collectively within the Greek city, from the 90's until today. My aim is to place each group within the theoretical frames I use; in addition, I focus on the actions of these groups to draw links between them. The main concepts I analyze, are: public art, public space and the public sphere and finally participative and political art.

To offer critiques of the action groups, I consider their perspective interaction, or otherwise association, with the public during the actions, their production of public sphere, their way of collective organization and their processes of action.

Finally, the role of Public Art in the Greek urban space is described, in this research, as an element of the social, cultural and political urban tissue.