Thousands of nude cyclists have set off on a trek around the city for the annual Philly Naked Bike Ride.
Organizers say about 3,000 riders in various stages of undress on Saturday planned to pedal a 10-mile (16-kilometre) course taking in sights including Independence Hall and the Philadelphia Museum of Art, where Sylvester Stallone sprinted up the steps while training as Rocky.
Participants in the ride can go as bare as they dare. Some are in their birthday suits while others are sporting underwear or just body paint.
The ride is to protest dependence on fossil fuels, advocate for the safety of cyclists and promote positive body image.