Severe damage is visible in almost every building. A huge billboard with an image of a waving Russian flag stands next to the bridge that crosses the Oskil River in the center of the city, with the words, “We are one people with Russia!” For now, the Ukrainian military has chased Russian forces over the bridge and appears to be building some momentum pushing up the eastern banks of the river toward Luhansk, a key separatist region controlled by Moscow. CNN saw Ukrainian infantry returning from the east side on foot. Yet within this city, one of several in the eastern Kharkiv region that have been liberated, there are the telltale signs of a hellish occupation. A former police building was used as a massive detention center by the Russians, at one point holding up to 400 prisoners in its cramped and dark cells, with eight or nine prisoners per room, Ukrainian authorities told CNN. A painted mural of a Russian soldier with a “Z” on his armband, standing next to an old woman waving the flag of the former Soviet empire, is still visible on one wall. As authorities continue to search and clear liberated cities in the Kharkiv region, they are finding more and more evidence of detention centers and cells used for torture. Ukrainian President Volodymyr Zelensky said on Saturday that “more than 10 torture chambers” used by the occupation forces have so far been found in the region. “As the occupiers fled, they also dropped their torture devices,” he said. CNN reached out to the Russian government for comment, but did not receive a response. Kupiansk may have been liberated recently, but the city is a ghost town, marked by destruction and debris. The few locals who remain huddle in its empty shell. read more