This story illustrates how activating the theme of a significant past, in old urban districts, places both space and residents in a state of uncertainty. Using the cases of Irkutsk and Krasnoyarsk—two cities in Eastern Siberia with a combined population of nearly two million—we will examine the competing discourses surrounding the past of several historic neighborhoods that have become arenas of local “memory wars.” These discourses are shaped, on one side, by the local “urban political regime” and, on the other, by the residents of areas that powerful groups seek to claim. Both acknowledge that the contested space represents the past, yet they frame it differently: the former seeks to devalue it by labeling it “dilapidation,” while the latter enhances its significance by calling it “heritage.” The dominant narrative in this struggle determines the future of urban space: what is classified as dilapidated is demolished, whereas what is recognized as “cultural heritage” is preserved and protected. The final decision is typically made by state-accredited experts, who have the authority to formalize one interpretation of the past over another. These experts can delegate their power to actors with significant social or financial capital. The latter work to establish their preferred version of collective memory—whether as a “monument” or a “crumbling ruin”—through legal battles, media campaigns, and, at times, bribery, intimidation, and violence. Analyzing these urban “memory wars” allows us to see the Post-Soviet Siberian city as a text, in which “historical” space becomes a fluid signifier, and “history” itself emerges as one of the ways to legitimize power over it.