Circle C Metropolitan Park on Slaughter Creek is a City of Austin park along Mopac (Loop 1) by Slaughter and La Crosse in far southwest Austin. The main section of the park is along Slaughter Lane west of Escarpment, although the park continues east of Escarpment, across Mopac, all the way to Bowie high school.
The main features of the park at Slaughter and Escarpment are a huge soccer complex, a disc golf course, 4 or 5 miles of trails, and a playground.
The trails in this park are great for jogging or walking your dog, but don't really work for mountain biking. They only get interesting where they criss-cross the disc golf course - it's easy to get lost here, becuase the singletrack is basically the eroded paths of the disc golfers. There are a few nice stretches of single track on the west side of the park, but it never really flows together.
The park also includes the Veloway, although the Veloway isn't connected to anything else in the park, by design.