Dear Friends of the Giant Fiberglass Pineapple Overlooking I-95: Stop writing us letters! We would love to write 270 words about your fruit, only we haven’t the time. But you raise a good point: Express will never address more than a tiny fraction of our area’s unseen sites. These apps cover what we won’t.

Roadside America ($2.99, iPhone only)
If there’s a big version of a smaller thing, it’s listed. (The fiberglass pineapple is real, and in Baltimore.) Is it morbid in design, content or both? That’s Roadside’s favorite kind of attraction, leading to a high density of graves and religious sites. (The replica Roman catacombs in Northeast hit all the sweet spots.) Local users will encounter the 12-foot-wide, four-story Arlington Skinny House (711 N. Barton St.); the One-Time World’s Largest Chair, in Anacostia; and the Victims of Communism Memorial, in Capitol Hill. The Roadside Americans just released “Roadside Presidents” ($2.99), with points of interest such as “Where President Ford Lived for His First 10 Days as President.”

It Happened Here ($2.99, iPhone and Android)
IHH catalogs landmark events that are more conversation starters than destinations: The Ritz-Carlton hotel bar in Pentagon City, where Monica Lewinsky told a bugged Linda Tripp about her affair; places where scenes from movies (“Salt,” “Minority Report” and others) were filmed; the suburban Marshalls where former Congressman John Jenrette stole shoes in 1988. IHH also likes morbid, and some may consider it tasteless to include Beltway sniper shooting locations.

NPS National Mall (free, iPhone and Android)
Surely Smithsonian-bound tourists would gladly detour to see the plaque on Ohio Drive SW commemorating the 1918 launch of U.S. Airmail, or to admire neglected Founding Father George Mason, whose bronze effigy chillaxes in West Potomac Park. If not, the National Park Service’s app is plenty useful on the Mall proper, identifying the German-American Friendship Garden, the John Paul Jones Memorial and the future site of the Dwight D. Eisenhower Memorial.