This essay examines online representations of 9/11 within the context of contemporary cultures of public mourning and memorialization. Based on the study of visual as well as textual material from 9/11 memorial websites, this essay argues that such online representations effect a spatial and temporal telescoping of the event by calling upon a global audience to participate in the collective acts of recollecting, archiving and mourning the loss that occurred at the epicentre, Ground Zero. It further argues that the constant circulation of 'signs' from the actual site of the event in the 'virtual' world turns 9/11 into a chronotope and unites the users into an emotionally responsive, affective community of witnesses.