Do a 'stairs challenge' at a local stadium or park.

“What I did was loosely based on some of the old Parking Garage Workouts we used to do in Downtown Winter Park, except with zero equipment. There are exactly 100 stairs (counting each landing as 1 stair) and a big break after 70 stairs before the last 30 stairs to the very top. That flat, straight break area was perfect for adding a traveling exercise to the mix. It was fun to use the stairs for a workout, since there were several other people there doing the very same thing. At the peak, about 20 of us were doing our own workouts of various difficulties and intensities. One especially enthusiastic guy was doing frog leaps up the stairs!”