Walking Washington, D.C.. Barbara J. Saffir

       Start at the Russian Federation’s Embassy, 2650 Wisconsin Avenue NW. Its massive white building was designed by Soviet architect Michael Posokhin, who designed the State Kremlin Palace. Somewhere beneath Wisconsin Avenue NW is (or was) a secret tunnel that the FBI and the National Security Agency used to eavesdrop on the Soviets, wrote Pulitzer Prize–winning author David A. Vise in The Bureau and the Mole. FBI counterintelligence agent Robert Philip Hanssen warned the Soviets about the tunnel and a nearby house where the Feds monitored them before he was arrested for spying in 2001. An FBI spokesperson still says it “has never confirmed nor denied such a story.”

       With the embassy to the left, walk north on Wisconsin Avenue NW and turn right on Edmunds Street NW. When it dead-ends at Massachusetts Avenue NW, the Embassy of the Republic of Iraq is across the street to the left in a Tudor-style brick building. Turn right to pass the dignified stone homes of the Royal Norwegian Embassy and the Holy See’s equivalent, called an Apostolic Nunciature, on the left. On the right is the fenced campus of the United States Naval Observatory and the vice president’s home. It’s impossible to miss the red-numbered digital clock out front or the 2,000-foot-diameter Observatory Circle on a map. The Navy needed that buffer to protect its clocks from the vibrations of horse carriage traffic when it moved to the then “dark-sky” outpost in 1893, said spokesman Geoff Chester. Today’s traffic doesn’t faze its Master Clock, a bank of 100 atomic clocks that keeps precise time for the military, one of the observatory’s chief functions. (The National Institute of Standards and Technology is America’s civilian timekeeper.) Visitors can register online to peer through a telescope and explore the round rare-book library designed by Richard Morris Hunt (who designed North Carolina’s famous Biltmore estate) if they can snag one of the extremely limited post-9/11 astronomy tours. They won’t see the vice president’s three-story Queen Anne house, which was built for the superintendent in 1893.

       Across the street is the Embassy of Finland, built in 1994, with its copper-clad walls and ivy-covered trellis. Its interior also blends the Machine Age and nature with blonde-wood floors, a wooden sauna, and a rear two-story window wall framing towering tulip poplars and other trees along Normanstone Parkway. Finland regularly hosts exhibitions, and it invites visitors to register online for a monthly tour of its green building, one of two platinum LEED-certified embassies in the world, the embassy says.

       Just past the Naval Observatory is the British Embassy on the right. Queen Elizabeth might wince if she saw the hundreds of commoners pouring into the ambassador’s staid brick country house, designed by Sir Edwin Lutyens, and traipsing through the formal gardens during the unusual access throughout the annual EU Open House. But Anglophiles can’t get seem to get enough of the royal compound, even without cherubs from the nearby British School serenading them or the goodies from Union Jack’s Pub. After all, it is America’s motherland.

       Pass the neoclassical Embassy of South Africa on the left and the cantilevered modern Embassy of Brazil on the right. Turn right on Whitehaven Street NW for the massive Embassy of Italy on the corner. The sculptural structure with its small punctuated windows is an “abstract rendition of a Tuscan palazzo,” the American Institute of Architects says. It also expresses D.C.’s original map, with two right triangles (Virginia and Maryland) separated by an atrium (the Potomac River). Italy hosts gobs of public events.

       At the end of Whitehaven is a private embassy on the left, a trailhead to Dumbarton Oaks Park in the middle, and a former president’s private residence on the right. President William “Bill” Jefferson Clinton, the first president with an email address, and Hillary Rodham Clinton, who hopes to become America’s first female president, bought the brick Georgian-style house in 2001. Across the street is Denmark’s 1960 glass and Greenland marble embassy.

       Return to Massachusetts Avenue NW and continue south for the Islamic Center on the left, with its 160-foot minaret. The center welcomes visitors to its bookstore and its eye-popping gilded mosque with blue Turkish tiles and Moroccan stained glass. While it’s not an embassy—Egypt, Pakistan, Saudi Arabia, and other countries built it in 1957—the mosque independently runs a bazaar with homemade food and crafts during Passport DC.

       Turn left on shady Belmont Road NW and right on Kalorama Circle. Each Goldilocks-size stone or brick mansion seems more luscious than the last in this early 1900s residential enclave. Turn left on Kalorama Road NW for the private, park-side estate of the French ambassador on the left. French-born Jules Henri de Sibour created this 23,000-square-foot manor house in 1911 for lead-paint manufacturer William Watson Lawrence. The French government bought the brick and stone showplace in 1936. Katy Perry and Kevin Spacey are just two of the droves of celebs who have partied there. They attended the Vanity Fair–Bloomberg blowout after the 2013 White House Correspondents’ Association Dinner.

       Stay right for 23rd Street NW and turn right on Wyoming Avenue NW to pass several embassies. Turn left on Kalorama Road NW; turn right on Tracy Place NW; turn left on Belmont Road NW; and turn left on Massachusetts Avenue NW for the Embassy of Japan on the right. Behind the Georgian Revival mansion that Japan built in 1931 is its Ippakutei teahouse, which the embassy calls “the greatest of its kind outside of Japan.”

       Continue south and turn left on S Street NW for The President Woodrow Wilson House on the right. Thomas, the 28th president’s first name, and his wife, Edith, lived there after he left the White House in 1921. The Georgian Revival brick house is virtually untouched from the days the Wilsons lived there, with their Steinway piano and wall-size Gobelin tapestry from France.

       Reverse direction on S Street NW and turn left on Massachusetts Avenue NW, past a nearly continuous stream of embassies in former mansions from D.C.’s Gilded Age around the turn of the 20th century. On the right, at Sheridan Circle and 23rd Street NW, is the residence of the ambassador of Turkey. Edward Hamlin Everett, inventor of the fluted bottle cap, built the White House–esque mansion in 1915. On the left at Florida Avenue NW is the prestigious Cosmos Club. Its ornate Indiana limestone façade was “inspired by the style of Louis XVI,”