I used to do "towers" in a five-story parking garage on nasty, rainy, dark, Oregon winter nights, up one tower to the top, down the ramp, up another tower, etc. until I had done 16 towers, and recovered gently down 16 ramps. No pounding, good for quads, as hard aerobically as you wanted it to be. Seems like an even better option for dark, snowy, icy nights in harsher weather environments. The lighting is another advantage.
I also found that after a hard half-marathon effort that left me sore way up into the groin because of intensity/duration demands of the race, I would often be hobbling for a week until I discovered that even gentle running up flights of stairs got blood flow in and out of those "racing muscles" that no amount of easy running on flat surfaces could touch. Stairs seemed to be the perfect easy recovery run for that particular problem.