Ritan Park is one of Beijing's greatest green lungs, the other being Tiantan (Temple of Heaven) park. Like Tiantan, Rtan is the site of an altar that was used by Chinese emperors to pray to specific deities ( in this case the sun) for good fortune and abundance. Unfortunately, unlike the other altars around Beijing, the actual altar site at Ritan is closed to the public.
But, that doesn't mean that there's nothing to do at Ritan Park. Ritan park is in the heart of the embassy district and as a pleasant result is home to numerous restaurants offering everything from Chinese fare, to Russian and German home-cooking. The park is also home to numerous bars, including the stone boat, a cheap and fun watering hole inside the park itself.
The park also offers options for those with a more active streak. Ritan park is a great place to meet a kungfu or tai chi instructor, there are many instructors, who speak english teaching in Ritan park ( check the Beijinger for specifics). Also you find caligrphers, traditional dancers, and a climbing wall.
The park is open from 7am to 9pm. Admission is free. to get to the park, go north from Jianguomen subway station along Ritan Lu, this will take you to the southwest corner of the park. from here turn right and walk a block and a half, until you reach the main gate.