The Rock Creek Park contains a beautiful wild forest and serves as an oasis for city residents and tourists. Attractions include picnic areas, winding trails and bike paths, a nature center, a public golf course, tennis courts and stables. The centerpiece is a working gristmill, complete with a turning water wheel. Rock Creek Parkway runs alongside the meandering creek. Parts of the road are closed to traffic on weekends and turned over to cyclists and roller bladers. Although the Metro is nearby, a car is required to visit many of the key sites in a single trip. The park is also a popular spot in the winter for sledding, snowballs and other outdoor merriment.