Jeff Greenwood is a skateboarder and creator of Concrete Disciples, as well as the current website administrator of The Skateboarding Hall of Fame, among many other things, like the OG Skate Jam and more. Concrete Disciples has been tracking the develompment of skateparks around the world over 25 years. Jeff has a great back story growing up in California and skating and building ramps with some of skateboarding"s biggest names. A lot of great stuff here for you skateboard historians.