Virginia law draws a very sharp distinction between cities and other communities. Since 1871, all communities incorporated as "cities" have been legally separate from counties. The only other form of incorporated community in Virginia is the "town", which is always contained within a county.
Annandale Home to DC's "Koreatown" and some of the best Korean food you'll ever have outside of Korea.
From Washington, DC go South on on I-395 or I-66. Or cross on Memorial Bridge, Key Bridge, or Chain Bridge, to the George Washington Parkway. Or take I-295 South to I-95 South/I-495 West, and cross the Wilson Bridge.
From the Northeast including Southeast Washington DC, Prince George's County, and Baltimore: take I-95 South/I-495 West, across the Wilson Bridge. Or, take the Baltimore-Washington Parkway (I-295) South, connect to I-95 South/I-495 West, and cross the Wilson Bridge.
From the Northwest (Montgomery County, MD) take I-495 South, across the Legion Bridge.
The National Capital area (including Fairfax County) is the 9th largest metropolitan area in the U.S., but has the 5th worst traffic congestion in the U.S. 
Both I-95 and U.S. Route 1 pass through Fairfax County, on their way from Maine to Florida.
I-95, the major North-South Interstate on the East Coast, joins the I-495 Beltway to points South, at the Springfield Interchange (a.k.a. the Mixing Bowl).
The Southwestern portion of the Capital Beltway (I-495) runs through Fairfax County. The Legion Bridge connects to Montgomery County, MD, in the North. The Wilson Bridge connects to Southeast Washington, DC, and Prince George's County, MD, to the East.
I-395 runs from the Springfield Interchange Northeast to Washington, DC.
I-66 runs from the West to Washington, DC.
U.S. Route 1, the original North-South highway on the East Coast, runs due North through Alexandria and Arlington to Washington, DC, and South to Prince William County, VA, passing through downtown shopping districts all the way.
U.S. Route 50, the original East-West transcontinental highway, passes through Fairfax County on its way from California to Maryland. It joins I-66 to cross into Washington, DC, on the Roosevelt Bridge.
Fairfax County Parkway is a North-South highway, West of the Beltway.
Inside the Beltway, major streets move in seemingly random directions, with heavy stop and go traffic. It may seem as though they're all named Chain Bridge, Lee, and/or Jackson!
Gunston Hall, the Colonial estate of George Mason, author of the Virginia Declaration of Rights. 
Old Town Alexandria The main street of Alexandria's Old Town is King Street. Old Town's cobblestoned steets have nearly 4,000 buildings dating from the 1800s and 1700s, some dating back to the 1600s. It is filled with shops and good restaurants. Some tourists use Old Town (or other parts of Alexandria) as a "home base" for D.C. trips, and it's a popular weekend destination. Tour boats, that go north to D.C. and south to Mount Vernon, leave from Old Town. Many hotels in the area run free shuttle buses to the King Street Metro.
Gadsby's Tavern Museum in Alexandria's Old Town. The first five presidents — Washington, Adams, Jefferson, Madison, and Monroe — were customers. A U.S. National Historic Landmark, now operated as Gadsby's Tavern Museum, a cultural history museum. The Tavern houses exhibits of early American life in Virginia, and a restaurant in the original dining room, serving a mixture of period and modern foods.
Elizabeth Hartwell Mason Neck National Wildlife Refuge
Wolf Trap National Park for the Performing Arts
National Firearms Museum at the National Rifle Association Headquarters, in the City of Fairfax 
Steven F. Udvar-Hazy Center - National Air and Space Museum, 14390 Air & Space Museum Pkwy., Chantilly, ph: (202) 357-2200. Located near Dulles International Airport, this museum houses many air/spacecraft, including the SR-71 "Blackbird" spy plane, the Concorde supersonic jet and the space shuttle "Enterprise". Parking is available for $12/vehicle. Additionally, a shuttle is available from the Air and Space Museum downtown. Prices range from $5 to $7 depending on number of tickets bought. 
Fair Oaks Mall, 11750 Lee Jackson Highway, Fairfax, VA 22033. Anchored by Macy's, Lord & Taylor, Sears, and JCPenney.edit
Fairfax Corner, Monument Dr. & Government Center Parkway, Fairfax, VA 22030. edit
Fairfax Square, 8075 Leesburg Pike, Vienna, VA 22182. Designer shopping including Tiffany & Co., Gucci, Louis Vuitton, and Hermes of Paris, and Elizabeth Arden's Red Door Salon & Spa.edit
Reston Town Center, 11921 Freedom Drive Suite 100, Reston, VA 20190. Designed as a traditional downtown cityscape, not an enclosed mall. Dine al fresco at Fountain Plaza in the Summer, or skate in the outdoor rink in Winter.edit
Springfield Mall, 6500 Springfield Mall, Springfield, VA 22150, ☎ 703-971-3600. Anchored by JCPenney, Target, and Macy's. edit
Tysons Corner Center, 1961 Chain Bridge Rd. Suite 105, McLean, VA 22102, ☎ (703) 847-7300. Since 1968, one of the first super-regional malls in the country, still one of the premier shopping malls on the East Coast. Anchored by Nordstrom, Bloomingdale's, Lord & Taylor, and Macy's. edit
Tysons Galleria, 2001 International Drive, McLean, VA 22102, ☎ (703) 847-7300. Upscale shopping and dining at designer retailers including Gucci, Cartier, Chanel and Versace. Saks Fifth Ave, Neiman Marcus!edit
Grevey's Restaurant, 8130 Arlington Blvd Falls Church VA, ☎ 703) 560-8530. edit
Sunset Grill, 7250 Columbia Pike Annandale, VA, ☎ 703.658.0928, . "The inland beach bar"edit
Sweetwater Tavern, 3066 Gate House Plz Falls Church Va, ☎ (703) 645-8100, . edit
Vienna Inn, 120 Maple Ave E Vienna, Virginia 22180 (Off 123 5 minutes from Tysons Cornor), ☎ (703) 938-9548. Hole in the wall bar, around since 1960. Very popular with locals, cheap and terrific food, especially their chili dogs.edit
Residence Inn Herndon/Reston, 315 Elden Street Herndon, VA, ☎ (703) 437-4007, . edit
Washington Suites Alexandria, 100 S. Reynolds Street Alexandria, VA 22304, ☎ 703-370-9600, . checkin: 3:00; checkout: 12:00. Located in the West End of Alexandria close to Springfield, Fort Belvoir, Old Town Alexandria, 9 miles from Washington DC.edit
Homewood Suites by Hilton Falls Church - I-495 @ Rt. 50, 8130 Porter Road, Falls Church, Virginia, 22042, USA, ☎ 1-703-560-6644, . checkin: 3:00 pm; checkout: 12:00 pm. Free shuttle service to metro. Free breakfast daily and dinner and drinks served Monday - Thursday. Hotel also offers free WiFi.edit
Next-door Arlington features the Pentagon, and Arlington National Cemetery.
Alexandria also borders Fairfax, and has a beautiful historic district on King St, by its port on the Potomac.
Washington, D.C. is just across the Potomac River, featuring the Washington Monument, Lincoln Memorial, Jefferson Memorial, Smithsonian Institution, White House, US Capitol Building, Supreme Court, Library of Congress, and much more.