Year 15 (XV) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Caesar and Flaccus (or, less frequently, year 768 Ab urbe condita). The denomination 15 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

The Plus 15 or +15 Skyway network in Calgary, Alberta, Canada, is the world's most extensive pedestrian skywalk system, with a total length of 18 kilometres (11 miles) and 62 bridges. The system is so named because the skywalks are approximately 15 feet (approximately 4.5 metres) above street level. (Some Plus 15 skywalks are multi-level, with higher levels being referred to as +30s and +45s.)