This is probably one of the most popular running routes in DC. The run starts off at the corner of the White House by New York Ave and 17th ST NW. I head south all the way down to Constitution Ave and then make a left. This first part is downhill. Then you can zig zag just a little bit run down the grassy area of the National Mall. Proceed all the way down to the Capitol building. When you get past the man-made lake at the Capitol building you have a choice to head up the left side or cut it short in front of the building. If you head up the left side, you have a nasty uphill climb, but the payoff is great. You get the backside of the Capitol building and then can cruise downhill on the far side.
On the way back, I run along the south side of the National Mall past all the museums. It’s a great run for sure, but I would not do this route during the day on a weekend as it gets backed with tourists. You end up running around crowds of people and get really annoying. Middle of the week, earlier in the evening, this is the ideal run — like 730pm on a Tuesday. You’ll see dozens of other runners out with you doing similar routes.
And finally, the hill you ran down in the beginning near the White House is the uphill victory hill to finish off the run.