Since the late 1990s, with the growth of new media technology and relational aesthetics as well as the renewed interest in the history of places, spatial art practices have expanded to include in situ installation art, relational interventions, immersive environments, intelligent architecture, augmented reality, and Internet localizations. This expansion has set about a significant rearticulation of the aesthetics of space, one in which artistic practices invested in the critique of space have moved away from the demythologization of space of the 1970s and 1980s (the disclosure of the doxa of specific environments) to engage with what might be called the activation of sites-an activation that calls for the mobilization of the spectator and his or her participation in the making of the artwork.The shift has been a progressive yet persistent one. Sitespecific activities emblematic of the 1970s, 1980s, and early 1990s concurred to problematize the notion of space as a passive receptacle of objects and subjects. This problematization took different forms. It included the Minimalist integration of the gallery space in the spectator's perceptual experience of the art object as well as institutional critique, the turning of space into place, the production of countermonuments, and the unfolding of site as what art historian Miwon Kwon, in her influential One Place after Another: Site-Specific Art and Locational Identity (2004), identified as a discursive (a vector rooted in language and context).1 Many of these practices shared the democratic impulse to disclose what art historian Rosalyn Deutsche in her equally influential Evictions: Art and Spatial Politics (1998), which includes an exemplary analysis of Krzysztof Wodiczko's installations, designated as the hidden conflicts and exclusions constitutive of social space.2 In the last two decades or so, this impulse has not so much disappeared but instead has been rearticulated, with varied success, in media practices that explore mobility, movement, communality, corporeality, and affectivity as modalities by which space can be mapped, known, or simply felt through the actual experience of that space. In most cases, the activation of space requires the mobilization of the spectator inside or outside the gallery space and often relies on new media technology to do so. In terms of exploring the mobilization of the viewer as a form of emancipation of the spectator, recent media art's activation of space has its roots in expanded cinema practices of the 1960s and 1970s-practices that seek to break away from the corporeal immobilization and black boxing of film spectatorship.3 Activation also requires a greater participation from the spectator in the production of environments-one recent example being Thomas Hirschhorn's 2013 Gramsci Monument in which a team of residents of Forest Houses in the South Bronx was invited to transform their district into a live monument.Although several art historical studies have started to examine this spatial shift,4 the redefinitions that it appears to entail-redefinitions of spectatorship, perceptibility, criticality, spatial politics, mediality, and temporality-remain insufficiendy addressed. Key to the rearticulation is the blooming of the aesthetic exploration of spatial interfaces provided by mobile technologies (books, maps, Walkmans, CD players) as well as the exploration of contemporary mobile media endowed with location-awareness applications (Wi-Fi, the triangulation of location by radio waves, smartphones whose localization capacities are enabled by the Global Positioning System [GPS]). There is no real understanding of contemporary spatial art without an assessment of these media art developments. Let us briefly refer to the following two works: (1) Jeremy Hight, Jeff Knowlton, and Naomi Spellman's image and sound location-aware narrative 34 North, 118 West (2002), which unfolds on the basis of participants' location and movement in space while equipped with headphones and a Tablet PC with a GPS card, so as to uncover the history of the industrial era of Los Angeles, and (2) Rafael Lozano-Hemmer's Open Air (2012), an interactive artwork held in Philadelphia's museum district whereby participants, using an iPhone application, could register messages played back loud over the site and then contemplate the modulation of light rays projected across the sky by robotic searchlights that react, in brightness and position, to voice frequency and volume as well as to GPS localization. …