The Traveling Rings or Swinging Rings are New York City's most unique and unconventional outdoor workout equipment. The facility located at the bottom most tier of Riverside Park at approximately 105th street. It is comprised of a large sandbox containing two metal arched frames. Each frame has a series of 10 rings which are spaced approximately 5-8 feet apart from one another and about 6 feet off the ground.
The goal is to be able to swing from one ring to the next using a combination of strength and technique. On any given late-Summer afternoon you will find acrobatic individuals demonstrating skilled and artistic methods for crossing the rings and back. A simple youtube.com search will provide you with numerous examples of what is possible on these rings.
The second set of rings is much smaller and lower presumably designed for children.
While the rings are not necessarily designated for conventional bodyweight strength workouts it is possible to perform pullups, front levers, hanging leg raises and other bodyweight exercises on them. Do bear in mind that you will have to use the full extent of your wingspan in order to grab both adult rings at once. Working out on the children's rings may be somewhat easier although most adults will have to bend their knees in if they wish to workout. Of course please be kind and get out of the way if the kids are practicing there.
NOTE: Using climbing chalk will greatly enhance your experience working out or swinging from these rings and I highly advise using it.