There are numerous local parks within Champaign/Urbana and in surrounding areas that contain hills suitable for wintertime sledding.

Centennial Park

Location: Corner of Kenwood & Kirby, Champaign, IL

A popular, but classic, destination.

University of Illinois Arboretum

Location: South Orchard St., Urbana, IL

This park has a large bowl-shaped hill. You can slide off either side (into the bowl or off the back of it).
A popular destination for university students to sled. 

Bowl/inside/South side

Back/outside/North side