Myrtle's an urban trekker. Says the true frontiers are the cities, so she explores 'em. Scaling skyscrapers, spelunking in abandoned subway tunnels, mounting expeditions into condemned buildings to collect artifacts. That sort of thing. . . .
You Still Can't
The first seven photographs are by Michael Cook, and are found on his website The Vanishing Point - "Maps, photographs and studies of sewers, hydroelectric tunnels and other underground infrastructure in Ontario and further afield."
The final three photos are taken by urban explorers in Europe, and are found at International Urban Glow.