I was there about 7? years ago. Next to the spanish library of medellin, which was up on a hill, there was a tiny little skate bowl. If you find it, it will probably be the best view you ever skated. It looks down on the whole city. I was sipping some crazy sugar cane juice and watched kids play soccer in it.
Colombia is so awesome. Highly recommend the Botero museum, if you like art.