Being, space and time are merged together into the happening’s title, “da:sein”, which aimed to invoke the reassessment of the most prominent existentialistic questions that WE, as part of an inescapable collective of constantly shifting values, carry within. A group of individuals placed within a space, “deprived” of any previously mentioned values, as an anomaly within the existing system, become an active-reactive organism, without no expectations of a predefined outcome. The simultaneously tangible and intangible product as a result of the six-hour happening, propelled the need of rethinking the process of appearance, formation and existence of a collective being and also the idea of how we affect and change the given habitat around us for later engagement with the audience. The happening was realized at the opening of the Actopolis apartment in Belgrade on 6 May 2016, which marked the public part of the Belgrade program of the international Actopolis project. For this occasion, the apartment in Dorćol neighborhood was transformed into a common space where the majority of public programs by 14 artists and artistic collectives who participated in this project (with the main topic of self-organization) took place. The participants of the “da:sein” happening registered via email and agreed to the terms and conditions that their movement and actions would be restricted only to the inner space of the apartment for a period of six hours, from 2 p.m. till 8 p.m. After that period, the doors were opened and the audience was encouraged to talk to the participants and share their gained experience. In total, there were 12 participants in the happening, including a dog. During the time of the performance, the space was emptied of distracting elements and only a few objects remained, including some chairs, tables and an old piano. Materials such as paper, chalk, pens, colors, tape, an audio recording device, cameras, etc. were provided as means for self-expression. A large variety of food and refreshments was also provided for the participants and some of them used them as a means of expression in communication with the other happening’s participants and later the audience. The final goal of this event was to evoke their inner consciousness in participants, i.e. the reason of their existence – something that Martin Heidegger, a German philosopher called dasein, hence the name of the happening. Trough confinement within a given space, a person starts to interact with the people and space who surround him, sharing this experience both with the other participants as well as himself, creating an isolated microsystem within a barely comprehensible macrosystem. Having been locked for six hours, the happening participants had an opportunity to share their experiences with numerous audience and the media. *Dasein (noun; German) – being, existence; (verb; German) – to be present, to exist. The happening was realized in colaboration with Andrea Rondović from the Faculty of Technical Sciences, department of Scene Architecture, Technique and Design from Novi Sad.