A number of months ago I found a video on You Tube that included individuals demonstrating Parkour on Roosevelt Island. In essence parkour is the application of gymnastics to urban landscapes. To first appreciate the art I would recommend the following short documentary. I love when they film the British children for their reactions to watching the tracuers.
Direct YouTube Link by SlamCamSpam
The videos I found that include individuals performing Parkour on Roosevelt Island among other NYC locations include the following two You Tube submissions.
NOTE: My presenting these videos does not suggest I am encouraging the use of public space or facilities in this manner as Parkour can be dangerous for those apparently not skilled in its application and may also be seen as a mis-use of the facilities pictured.
Direct YouTube Link by Whatismyleoname
Direct YouTube Link by Sophmore3000