This Smithsonian museum is somewhat off the standard sightseeing route (most other Smithsonians are located on or near the National Mall), so it doesn’t capture as many visitors as the other attractions. If you’re at all interested in the romance and adventure (that’s right, I said romance and adventure!) of the story of U.S. mail correspondence and its delivery, and in the international artistry and invention of that most miniature of art forms, the postage stamp, you really need to venture in.

You’ll find yourself in the elegant lobby of the historic structure (home of the Old City Post Office), where a welcome center and the relatively new (opened September 22, 2013) William H. Gross Stamp Gallery are located. The original part of the museum, where America’s postal history is on display from 1673 to the present, lies just past the information desk, downstairs. Unless you’re a philatelist, I’d recommend starting your tour in the original downstairs gallery.

Children usually make a beeline to the enormous blue freightliner truck front over in the corner, and climb up into the driver’s seat. This is part of the central exhibit area called Moving the Mail, and you’ll see planes, trains, and other postal vehicles, even a handcrafted hickory Alaskan dogsled, that have been used at one time or another to transport the mail. In Binding the Nation, visitors can follow a path through a forest to trace the steps of mail carriers who traveled from New York to Boston in 1673, and climb into a stagecoach headed west. The exhibit introduces famous figures, like Buffalo Bill, of Pony Express renown, and Henry “Box” Brown, who “mailed” himself, a slave, to an abolitionist in 1856.

Other exhibits cover mail’s impact on city streets and rural routes (Customers & Communities), the journey a single letter takes through the postal system and how that process has changed over time (Systems at Work), and the history and current practice of getting mail delivered to and from military personnel (Mail Call). In June 2014, the museum’s latest exhibit opened, Behind the Badge, which reveals the work of the U.S. Postal Inspection Service.

Return upstairs to explore the William H. Gross Stamp Gallery and be impressed by the fact that the museum’s six million–piece National Stamp Collection is the world’s oldest intact national stamp collection. Interactive kiosks, videos, and activities keep even the non–stamp collector interested, even amused. The World of Stamps exhibit features a hit list of famous stamps, starting with the very first postage stamp, the 1840 Penny Black, bearing a young Queen Victoria’s profile. On temporary loan until 2018 is the world’s rarest and most valuable stamp, the British Guiana One-Cent Magenta, which was sold for $9.5 million in a February 2015 auction to famed shoe designer Stuart Weitzman. Stamps Around the Globe displays international stamps, which make up half the Postal Museum’s overall collection (everything from a colorful 1965 Rwanda stamp displaying Cape buffalo to a delicate rose-tinted coat of arms on the 1859 stamp from the German state of Lübeck). Viewing these miniature artworks is a thrill. Don’t miss the last room, the Postmasters Gallery, housed in a gorgeous, six-sided paneled room, and reserved for special exhibits, like the one on view starting in April 2016: 100 Years of National Parks, which celebrates the centennial of the Park Service with displays of relevant stamps and mail tales.

Tip: The Postal Museum’s wall of windows features replicas of 54 historic U.S. stamps; come by at nighttime and you’ll see the artwork illuminated within the building’s facade.