O Museum in the Mansion (Mansion on O Street)

Landmark

Tucked in a quiet grove behind the National Academy of Sciences, this 12-foot bronze Einstein holds a tablet inscribed with three of his own equations — and at his feet is a star map of the sky on the exact night the memorial was dedicated in 1979, accurate down to the planets. Almost nobody detours the 200 feet off the Mall to find it.

Landmark

This is the largest Catholic church in North America and the tallest habitable structure in DC — taller than the Capitol dome — yet it sits in a residential Northeast neighborhood most Mall-bound travelers never drive through. Inside, more than 80 chapels and mosaic domes represent immigrant Catholic communities from Lithuania to the Philippines, each one a small embassy of someone's homeland.

Hidden gem

A working carriage-house alley in Shaw hides DC's best open-air gallery: a rainbow L-O-V-E mural spread across four garage doors, a mosaic tribute to Sun Ra and Erykah Badu, and murals honoring the Black working-class families who once lived here — all painted directly onto everyday garage doors since 2015.

Outdoors

Every mile marker for the next 184.5 miles to Cumberland, Maryland counts up from this exact spot — a flat towpath that a mule once dragged coal barges along, now a flat, shaded, stroller-friendly walk starting steps from Georgetown's restaurants. Walk half a mile and you're already further from a car than most of DC ever gets.

Outdoors

Beatrix Farrand designed the famous formal gardens next door, but she also shaped this wilder 27-acre streamside annex — and then let it go, deliberately, into overgrown naturalism as a hidden coda to one of America's great garden designs. Walk down the sloped lane from R Street and the manicured Georgetown gardens dissolve into Rock Creek's forest within a few hundred feet.

Attraction

The last city-owned public market standing in DC, rebuilt board-by-board after a 2007 fire — Saturday mornings mean blue-corn pancakes inside and a flea market of five continents' worth of dealers spilling onto the sidewalk outside.