Lookout Hill
This is arguably the second highest point in Brooklyn. The top is a compost heap so it keeps moving.
I would never recommend this for training purposes. The stairs are uneven in every dimension. They are of different heights, lengths and they are banked and crooked. Many of them are also broken. The "landings" between stair cases are poorly paved and full of puddles and rocks. This is one of the most poorly maintained parts of Prospect Park. It might be a nice place to go at the end of a long run, just to "chill out" but I would not go on a regular basis.
Have I made myself clear? Don't sue the Prospect Park Track Club, ChickenUnderwear or Google Blooger if you fall there. It is not a good place to run, or practice stair climbing.
See, it does not even look that nice. Disappointing....
It looks better from orbit