Our nation's capital offers tons to do for little price.

National Building Museum
The lobby of the National Building Museum
| Credit: Van Chaplin

With more free museums, monuments, and sites than any other American city, Washington, D.C., is a great place to escape for an affordable weekend.

Who knew that D.C. is home to the country's longest-running seafood market? Tucked into the banks of a Potomac River side channel, the Maine Avenue Fish Market is a bustling collection of wharfs and semipermanent floating seafood stalls. The shouts of "Spiced shrimp!" from vendors and the smell of crab boil soon had us famished, and we lined up with the locals at Jimmy's Grill, carrying paper plates of crab cakes and cups of strawberry lemonade ($29) to a stand-up plywood counter with river views. After lunch, we made our first-ever family trip to the National Gallery of Art.

Thanks to a new, free audio tour for kids, Luther and Eliot raced from gallery to gallery in the West Building as if on a scavenger hunt. While my wife, Heather, and Eliot explored the gallery's Sculpture Garden (home of the colossal and quite odd Typewriter Eraser, Scale X), Luther and I checked into Embassy Suites. Its weekend rates from $179 are a bargain compared to weekday rates that can run $100 more a night. We nearly blew our budget at Jaleo ($150), a bustling tapas joint on 7th Street, three blocks north of the National Mall.

After a complimentary breakfast in the hotel restaurant, we checked out and stored our bags with the bellhop ($5 tip). Next, we split up. Heather and Eliot walked along the National Mall, taking a couple of spins on the carousel ($10). Eliot, always an original, chose a blue-winged dragon to ride rather than a pony. Meanwhile, Luther and I visited the International Spy Museum ($33 admission for the two of us). He loved the glass cases filled with espionage relics—a camera hidden in a topcoat button and courier shoes with hollow heels. Just when we thought the kids might have grown tired of museums, we found an unlikely highlight at the National Building Museum. Its LEGO Architecture: Towering Ambition exhibit (through September 5, 2011) features towering models of 15 buildings from around the world made by LEGO artist Adam Reed Tucker ($20 for four).

Famished, we picked up our car at the hotel and drove north on Connecticut Avenue to Comet Ping Pong. The gourmet pizzas, hot out of a brick oven, and free games of Ping-Pong were nice diversions for antsy kids ($69).