Dalecarlia Tunnel

Dalecarlia Reservoir is the primary storage basin for drinking water in Washington, D.C., and Arlington County, Virginia. The reservoir is fed by an underground aqueduct in turn fed by low dams which divert portions of the Potomac River near Great Falls and Little Falls. The reservoir is located between Spring Valley and the Palisades, two neighborhoods in Northwest Washington, D.C., and Brookmont, a neighborhood in Montgomery County, Maryland.

The Washington Aqueduct is an aqueduct that provides the public water supply system serving Washington, D.C., and parts of its suburbs, using water from the Potomac River. One of the first major aqueduct projects in the United States, the aqueduct was commissioned by the U.S. Congress in 1852, and construction began in 1853 under the supervision of Montgomery C. Meigs and the U.S. Army Corps of Engineers. Portions of the aqueduct went online on January 3, 1859, and the full pipeline began operating in 1864.: 68 The system is owned and operated by the U.S. Army Corps of Engineers and has been in continuous use ever since. It is listed as a National Historic Landmark and the Union Arch Bridge, where it is listed as a Historic Civil Engineering Landmark.

Little Falls Branch, a 3.8-mile-long (6.1 km) tributary stream of the Potomac River, is located in Montgomery County, Maryland. In the 19th century, the stream was also called Powder Mill Branch. It drains portions of Bethesda, Somerset, Friendship Heights, and Washington, D.C., flows under the Chesapeake and Ohio Canal (C&O), and empties into the Potomac at Little Falls rapids, which marks the upper end of the tidal Potomac.

The Intelligence Community Campus-Bethesda (ICC-B) is a campus in Brookmont, Maryland containing offices for several agencies of the United States Intelligence Community. The campus was created in 1945 and initially served as the headquarters of the National Geospatial-Intelligence Agency and its predecessor organizations. In 2012, it was transferred to the Office of the Director of National Intelligence and substantially renovated into an architecturally and functionally modern design.

Sibley Memorial Hospital is a non-profit hospital located in The Palisades neighborhood of Washington, D.C. It is fully accredited by the Joint Commission on Accreditation of Healthcare Organizations, and is licensed by the District of Columbia Department of Health and Human Services. The hospital specializes in surgery, orthopedics, and oncology services. It has been part of Johns Hopkins Medicine since 2010.

The Marden House is a residence in McLean, Virginia designed by American architect Frank Lloyd Wright. It is located just off Chain Bridge Road and overlooks the Potomac River. Also known as "Fontinalis," it is named after Luis Marden (1913–2003), a writer, photographer, and explorer for National Geographic. It was designed by Wright in 1952 and was completed in 1959 at a cost of $76,000. The spot had caught Marden's eye in 1944 when he and his wife and had been fishing along the Potomac. After purchasing a plot of land, Marden continued the correspondence he had maintained with Wright since 1940, asking the architect to design a home for him. It was not until 1952 that the designs finally came. After Marden moved to a nursing home in 1998, the house was purchased by Jim Kimsey, co-founder of AOL, in 2000 for $2.5 million.

The Washington Waldorf School is a private K-12 school in Bethesda, Maryland, just north of Washington, D.C., on a 6-acre campus the school rents from Montgomery County. As a Waldorf school, the curriculum is based on the educational philosophy of Rudolf Steiner. Washington Waldorf School is one of over 1000 Waldorf schools worldwide and 150 Waldorf schools in North America. The school has one of the few outdoor kindergarten programs in the Washington, D.C., area.

Fort Marcy was a Union fortification protecting Washington, D.C. during the American Civil War. Its remains are now administered by the National Park Service as part of the George Washington Memorial Parkway in Fairfax County, Virginia.

The Chain Bridge is a viaduct which crosses the Potomac River at Little Falls in Washington, D.C. The steel girder bridge carries close to 22,000 cars a day. It connects Washington with affluent sections of Arlington and Fairfax counties in Virginia. On the Washington side, the bridge connects with Canal Road. Left turns onto the Clara Barton Parkway from the Chain Bridge are prohibited, but the reverse is permitted. On the Virginia side, the bridge connects with State Route 123 (Chain Bridge Road), which provides access to the George Washington Memorial Parkway. The Chain Bridge has three lanes (of which the center is reversible) and can be safely accessed by pedestrians and cyclists. The pedestrian sidewalk provides access to the Chesapeake and Ohio Canal towpath via a ramp. The bridge also carries water mains which provides Arlington County with water from the Washington Aqueduct.

Merrywood is a historic home located in McLean, Virginia on the Palisades overlooking the Potomac River that has hosted several presidents and members of the British royal family. The Georgian Revival style brick dwelling was built in 1919 for Newbold Noyes.

Fort Sumner was built during the American Civil War by the Union Army in the Brookmont section of Bethesda, Maryland, just northwest of Washington, D.C.

Pimmit Run is a 7.8-mile-long (12.6 km) stream in northern Virginia that runs from Fairfax County to the Potomac River at Chain Bridge in the Arlingwood neighborhood of Arlington.