Mentioned by washington.org
The 28 Most Romantic Spots & Things to Do in Washington, DC | Washington DC
"Couple in Rock Creek Park - Free Outdoor Activities in Washington, DC. Walk, jog or bike with your love through the rustic expanse of 2,100 acres that comprise Rock Creek Park. The historic park also includes attractions such as Peirce Mill and the Old Stone House, as well as a nature center, riding stables, tennis courts, a golf course, picnic areas and playing fields."