I quote from Wikipedia: "National Harbor is a 300-acre (1.2 km2) multi-use waterfront development on the shores of the Potomac River in Prince George's County, Maryland just south of Washington, D.C. near the Woodrow Wilson Bridge."
I remember many years ago when I was driving by this area to visit family friends in Oxon Hill, there was nothing there, just open space. Then it became this hip and "upscale" destination with hotels, restaurants, bars, and shops. They have fireworks (almost) every week. You can take the water taxi to DC and/or Alexandria. It's clean, fun, and safe. At least I think it's safe - they have security people at every block and corner plus the ones making their rounds on segways and patrol cars. They have a lot of events there. They're also building a Disney resort there - not sure when that would be completed. It's definitely worth a visit or two.
The harbor as we get closer.
The view down on the boardwalk.
I had crab cakes at this restaurant called Ketchup. I don't recommend it. The service was very poor. We waited at least 30 minutes before a waiter came by to get our orders, 45 minutes before the food came (we were close to walking out), no one came by to ask how our meal was, an hour to get the check, another 30 minutes to get our to go boxes and the waiter forgot the bags, so we had to ask the hostess on our way out for the bags because we didn't want to wait another 30-60 minutes for the waiter to come by. The food was ok and not worth the wait time, so go somewhere else.
The harbor at night.
We caught the fireworks show by the harbor.
Took pictures with the sunken giant sculpture called "the awakening".