“The DaVinci Code” taught us to look twice at Washington’s infrastructure, and indeed there is more than meets the eye. Plenty of secret and not-so-private meetings happen underground in tunnels and passageways connecting some of D.C.’s best-known buildings. Then there are the better-advertised subterrestrial sites: caverns, public transportation access and even a shopping mall. Whether you’re looking to rub shoulders with members of Congress, admire centuries-old rock formations or just grab a bite to eat, here are eight ways to see the region below street level.

wheaton-metro-crdtPhoto: qchristopher via Flickr 

U.S. Capitol Subway System
Metro isn’t the only way to get around underground. Three electric people mover systems connect the Capitol to the House and Senate office buildings. Open only to members of Congress and approved guests, you can hitch a ride during an official Capitol Tour.

Cost: Free
Where: East Capitol St., NE and First St., SE
When: Check website for availability
Online: visitthecapitol.gov

Library of Congress Tunnel
Feel like a Washington insider by walking this tunnel that connects the world’s largest library to the Capitol Visitor Center. Of course, a look at the reading rooms and guided tours above ground are also well worth the time.

Cost: Free
Where: First Street, SE
When: 8:30 a.m. to 5 p.m.
Online: loc.gov

Metro
The best-known of Washington’s below-ground spaces is the Metro, which began operating in 1976. It now has 118 miles of track serving 91 stations – 50.5 of those miles and 47 of those stations are subterranean. For added fun, ride the Western Hemisphere’s longest escalator (230 feet) at Wheaton station or stop at the deepest station (196 feet) in Forest Glen.

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Cost: $1.75 to $5.90, depending on distance traveled and time of day
Hours: Opens 5 am weekdays and 7 am weekends, closes midnight Sunday through Thursday and 3 am Friday and Saturday
Online: wmata.com

Union Station
Constructed in 1907, this is more than a place to catch a train – or bus or Metro. It’s also a shopping mall with and underground concourse, 130 stores, six restaurants, a food court and special events like the holiday train. Bonus: Take a self-guided tour using the Union Station Tour App.

Cost: Free to explore
Where: 50 Massachusetts Ave., NE
When: Stores are open Monday through Saturday from 10 am to 9 pm and noon to 6 pm Sunday; food court and restaurants vary
Online: unionstationdc.com

Luray Caverns
Stalactites, stalagmites and pools decorate the largest series of caverns in the eastern United States. Discovered in 1878, they’re easy to navigate now, with well-lit, paved walkways and a guide leading the way. Bonus: Listen to the Great Stalacpipe Organ, the world’s largest musical instrument.

Cost: $26/adult; $14/child ages 6 to 12; free for 5 and younger
Where: 101 Cave Hill Rd. (Luray, Va)
When: Tours begin daily at 9 am and end between 4 and 7 pm depending on the season
Online: luraycaverns.com

Skyline Caverns
Open to visitors since 1939, the caverns are a cool 54 degrees year-round and as deep as 250 feet below ground. Features include the unmoving Fairyland Lake, which mirrors the formations above it to create an optical illusion, and anthrodites – crystallike formations that are the only ones of their kind in America.

Cost: $20/adult’ $10/kid ages 7 to 13; free for kids 7 and younger
Where
: 10344 Stonewall Jackson Hwy. (Front Royal, Va)
When: 9 am to 4 pm or 6 pm, depending on the season
Online: skylinecaverns.com

Crystal City Shops
Take an urban stroll underground. Originally a subterranean mall, this has become a system of corridors and walkways lined with shops and restaurants and connecting the northern and southern ends of Crystal City. Grab a handspun shake at Good Stuff Eatery after browsing the Puppet Heaven store.

Cost: Free to explore
Where: 1750 Crystal Dr. (Arlington, Va)
When: 10 am to 6 or 7 pm Monday through Friday; 10 am to 6 pm Saturday; closed Sundays
Online: thecrystalcityshops.com

Dupont Underground
OK, so this is a work in progress, but the plan is to turn an abandoned trolley station 20 feet beneath Dupont Circle into an artistic haven (plus retail and dining) inside the 75,000-square-foot space that has sat empty since the 1990s.

Online: dupontunderground.org

Have you checked out any of these family friendly underground spots yet? Tell us about them in the comments below. 

—Stephanie Kanowitz