District of Columbia

Two decisions from two different centuries explain Washington's appearance. The first is the L'Enfant plan of 1791, which laid a system of broad diagonal avenues — each named for a state — across a regular street grid, connecting a network of circles and squares, with the Capitol and the President's House as the two anchors. That is why Pennsylvania Avenue runs at an angle between them, why the city is full of traffic circles, and why the addresses run in quadrants that confuse everyone for the first two days. The plan was refined a century later by a commission that cleared a railway depot and assorted buildings off the Mall to open the long green axis that exists now. The second decision is the Height of Buildings Act of 1910, which caps building heights in relation to the width of the street they face. It is a common misunderstanding that the limit is set by the Capitol dome; the mechanism is the street width, and the effect is the same either way — no towers, a horizontal skyline, and a city where the monuments still dominate the view. It also pushed the region's tall buildings across the river into Rosslyn and out to Tysons, which is why the Virginia skyline looks like a different city.

Massachusetts Avenue north-west of Dupont Circle carries the densest concentration of diplomatic missions in the country — some sixty of the city's embassies along a two-and-a-half-kilometre stretch, many of them in Gilded Age mansions the original owners abandoned when the city's summer social season faded. The quarter continues into Kalorama, Cleveland Park and Forest Hills, where the larger compounds sit, and it is a genuinely good walk: the architecture is extravagant, the planting is mature, and the national flags make it easy to read. Washington also holds the headquarters of the World Bank, the International Monetary Fund, the Organization of American States in its Pan American Union Building and the Inter-American Development Bank, which together give a few blocks west of the White House an unusual institutional density. Once a year in May, the Passport DC programme opens around fifty embassies to the public for free over two weekends — one of the best things the city does, and worth timing a trip around if the idea appeals. The Watergate complex on the river holds several missions and is an architectural landmark in its own right.

Northern Virginia begins immediately across the Memorial Bridge. Arlington National Cemetery rises on the hillside directly opposite the Lincoln Memorial, and a visit is quiet, orderly and moving: the Tomb of the Unknown Soldier with its continuously posted sentinel and the changing of the guard, the long view back over the river to the Mall, and Arlington House on the ridge above. The Pentagon and its memorial garden sit just east of the cemetery. Twelve kilometres downriver, Old Town Alexandria is a colonial port whose King Street runs from the waterfront up through preserved eighteenth-century blocks, with the Torpedo Factory — a former munitions plant turned working artists' building — on the quay and a good restaurant scene throughout. Another fourteen kilometres south, Mount Vernon is George Washington's estate above the Potomac: the mansion, the working farm, the reconstructed gristmill and distillery, and grounds worth a half-day in their own right. West towards Dulles, the Smithsonian's Udvar-Hazy Center is the museum's aviation annex, free to enter and holding a space shuttle, a Concorde and an SR-71 under one enormous roof — for many visitors it is better than the Mall building.

North and east of the District line, Maryland holds the region's water. Annapolis, fifty kilometres east on the Chesapeake, is the colonial capital of the state and the home of the United States Naval Academy, with the largest concentration of eighteenth-century buildings in the country, a state house that has been in continuous legislative use longer than any other, and a harbour full of masts — it calls itself the sailing capital of America and spends the season proving it. Baltimore, an hour north, is a full city rather than a day trip but works as one: the Inner Harbor and its aquarium, the cobbled streets of Fells Point, Fort McHenry on its point at the harbour mouth, and a food identity built on Chesapeake blue crab. Further out, the Eastern Shore towns of St Michaels and Easton are the slow-water version of the same landscape. The bay itself is the largest estuary in the United States, with thousands of kilometres of shoreline, and it shapes the region's cooking, sailing and weather. Closer in, the C&O Canal towpath begins in Georgetown and runs almost three hundred kilometres up the Potomac to Cumberland — flat, shaded and the best long walk or ride in the region.

Ninety minutes to two hours west, the land rises into the Blue Ridge and the region acquires mountains. Shenandoah National Park follows the crest for around a hundred and seventy kilometres, with Skyline Drive tracing the ridge from Front Royal south to Rockfish Gap and overlooks every few miles on both sides. The walking is excellent and well graded: Old Rag is the famous scramble and a long day, Hawksbill the high point, Whiteoak Canyon a chain of waterfalls, and black bears are common enough that the rangers will tell you how to behave before you ask. Autumn colour peaks from the middle of October into early November and is the busiest time by a wide margin — go midweek if you can. On the way out, Harpers Ferry sits where the Potomac and the Shenandoah meet at the corner of three states: a preserved nineteenth-century town on a steep wedge of land, with the Appalachian Trail passing straight through it and a national historical park interpreting its industrial and Civil War past. Antietam National Battlefield, north-west in Maryland, is a preserved landscape of fields and farm lanes with a visitor centre and a driving route. Further south, Charlottesville holds Monticello and Jefferson's university, both UNESCO-listed.

The capital region runs on a seasonal rhythm worth planning around. Spring is dominated by the cherry blossom — from a regional point of view, the important thing is that blossom weeks fill hotels across the whole DMV, not only downtown, and that the bloom forecast is published only about ten days ahead. Summer brings the outdoor season: the Wolf Trap national park for the performing arts in Fairfax County is the only national park dedicated to performance and programmes a full summer season under a timber-framed open-sided shed, and the Chesapeake sailing calendar runs from spring into autumn. Autumn is the region's quiet best — foliage in the Blue Ridge, comfortable city weather and thinner crowds. Winter is cold and grey but the museums are free and open every day except Christmas, which makes it the sensible season for anyone whose priority is indoors. Two regional dates worth knowing: the embassy open house in May, and the autumn foliage peak in the mountains, when the Skyline Drive can queue at the entrance stations on weekends.

The Metro is a regional system rather than a city one: its lines run out of the District into Montgomery and Prince George's counties in Maryland and Arlington and Fairfax in Virginia, which means a great deal of the DMV is reachable without a car, and the extension out to Dulles finally put the international airport on the network. Beyond the Metro's reach, two commuter rail systems fill in — MARC into Maryland toward Baltimore and Frederick, and the Virginia Railway Express south and west — both running from Union Station, which is itself the Amtrak hub for the Northeast Corridor and a Beaux-Arts building worth walking through. For everything else, this is driving country, and the Beltway that rings the District at a sixteen-kilometre radius carries some of the worst peak-hour congestion in the United States; the mountains, the Eastern Shore and Mount Vernon all realistically want a car. The three airports are covered in the city guide. One regional quirk: the District's quadrant addressing means the same street number exists four times over, so always check the NW, NE, SW or SE suffix before setting off.