The post-city, in the context of co-spatiality, is a meta-assemblage. Post-urban assemblage can be represented as a meta-geo-culture, whose local singularity turns out to be constantly transforming. The ontologies of post-urban geo-cultural assemblages (PUGCA) are reproduced as “floating” fields of the corresponding cartographies of the imagination. The post-city represents a pulsating cross-border mobile settlement of an assemblage nature. The inherent transborder nature of the PUGCA “erases” any possible exclusion/inclusion, transcending political meanings as co-spatial. Geo-cultural co-existence in the post-urban reality can be considered as the inclusion of any other post-urban geo-culture. Post-urban detournement as a contingent process leads to the formation of floating post-urban environments, whose images in an ontological sense cannot be accurately fixed. The formation of the PUGCA (in/of) Northern Eurasia may have an impact on the development of continental cartographies of the imagination of a planetary nature. It is necessary to talk about the long-term geo-cultural archetypes of urban environments (in/of) Northern Eurasia, which were formed on the territories of Russian states and became the basis for the development of specific, “North Eurasian” PUGCA. One of them can include a specific cross-border vernacular. The hybrid geo-cultural vernacular is a mental and material network of attitudes, discourses and images associated with the prevailing type of urban environments in Northern Eurasia. The North Eurasian variants of the hybrid geo-cultural vernacular can be a nutritious “soil” for the development of new forms of settlement. The cross-border nature of the North Eurasian hybrid vernaculars is associated with extensive limitrophic zones where large-scale civilizational platforms interact.