A street photographer is always devouring the city with their eyes. A global photo project on Instagram pushes them to do it for 24 hours straight. 24HourProject starts at midnight on May 25 and ends at midnight. If you participate, you post a picture every hour, with the hashtag, 24hourproject. The aim is to create a human portrait of the city.

Street photographer Suresh Naganathan, 38, a mid-level manager at a tech company, who took part last year, says, "It was one of the most exhilarating and challenging experiences of my life.