Tom Ryaboi has been dangling off rooftops since 2007. That’s when he started sneaking into downtown buildings (sometimes illegally) to photograph the city from unexpected, dizzying angles. In the last half-decade, Ryoboi’s unusual hobby has become a full-scale movement. Rooftoppers are normal twenty-somethings by day, intrepid urban explorers by night. “I think what’s important to look at here,” says Ryaboi, “is how people […] are challenging the perception of usable space. […] They’re treating their urban environment as they should, a place full of wonder and adventure.” Adventure is right: the photos on Ryaboi’s blog show the photographer and his friends clinging to scaffolding, striding along narrow railings and balanced on ledges—all hundreds of metres above Toronto streets. Here, 13 heart-stopping photos from the rooftopping pioneer.