The Plus 15 is Calgary's extensive network of enclosed, climate-controlled pedestrian bridges connecting buildings in the downtown core, elevated approximately 15 feet (about 4.6 metres) above street level—hence the name. With over 18 kilometres of walkways, Calgary's Plus 15 is the world's most extensive skyway network. The system allows people to walk between downtown buildings, transit stations, shopping, and services without going outside—particularly valued during Calgary's cold winters. The Plus 15 developed through agreements between the City and private building owners over decades. While offering weather protection, critics note it can draw activity away from street level.