Hidden Spaces, for instance, offered exclusive access to areas of Tai Kwun's heritage buildings that were opened to visitors for the first time. These included the second floor of E Hall, built in 1915. The tour group was led up a metallic staircase, typical of high-security prisons, for a viewing of the cramped prison cells from narrow passages surrounding the stairwell. Ki noted that for some years before 2006, when Victoria Prison was decommissioned, most of the inmates were remanded prisoners assigned to tasks in the prison's laundry workshop. The Laundry Steps next to E Hall - now an open-air venue for screenings and performances - used to be a slope to drain the water. The steps were added as part of the site's revitalization process, begun in 2008.

Hidden Spaces tourists also got the chance to visit an underground tunnel in the Police Headquarters Block. Built as an air-raid shelter in the late 1930s - almost as if in anticipation of the bombing that would destroy some of the buildings in the compound during the Japanese assault on Hong Kong in December 1941 - the 29-meter tunnel takes an unexpected turn, revealing an impossibly tiny hideout. With barely enough space to contain six people, this was meant for top-tier police officers, should Japanese forces infiltrate Tai Kwun and take over. They did.