I have 5 free days in Beijing at the end of August. What can I reasonably see and do?

I do not speak Chinese. I will be alone., on a limited budget. I am willing to travel to other areas as much as my time permits. I am interested in both natural wonders, like mountains, cliffs, and waterfalls, and ancient cultural sights. I do not want to go to the Great Wall because I will be taken there later--after my free time.