Boundary Channel

The Navy – Merchant Marine Memorial, located in Lady Bird Johnson Park on Columbia Island in Washington, D.C., is a monument honoring sailors of the United States Navy, Coast Guard, the United States Merchant Marine, the NOAA Commissioned Officer Corps and others who died at sea during World War I and other times. It was designed in 1922 by Harvey Wiley Corbett and sculpted by Ernesto Begni del Piatta, who died before it could be completed. It was cast in a foundry in Cleveland. Ground was broken on the memorial in 1930, with the foundation completed the following year and it was installed on October 18, 1934, but work on the base and landscaping was postponed due to lack of funding. A dedication ceremony was held on May 30, 1935. Funding was finally approved by Congress to finish the memorial in 1939 and work began anew the following September, to be completed by the end of the year.Nicknamed "Waves and Gulls," the memorial depicts seven seagulls above the crest of a wave. It is cast from aluminum and the base is made of green granite from New Hampshire (the base was originally concrete but replaced by the Works Progress Administration). It stands 35 feet (10.6 m) tall and 30 feet (9.1 m) wide. It is the first aluminum memorial in Washington, DC. The memorial reads: To the strong souls and ready valor of those men of the United States who in the Navy, the Merchant Marine and other paths of Activity upon the waters of the world have given life or still offer it in the performance of heroic deeds this monument is dedicated by a grateful people.

Washington Airport was the second major airport to serve the city of Washington, D.C., in the United States. Located in Arlington, Virginia, near the intersection of the Highway Bridge and the Mount Vernon Parkway (where The Pentagon's south parking lots, Metrobus bus bays, and a portion of Interstate-395 now exist). The first airport to serve the city was Hoover Field, a private airfield constructed in 1925. Washington Airport, a private airport triple the size of Hoover Field, was built literally across the road in late 1927. The airfield suffered from short and unpaved runways, numerous life-threatening obstructions around the field, poor visibility (due to a burning garbage dump adjacent to each field), and poor drainage. Washington Airport nearly went bankrupt in 1933, and it was auctioned off to a new owner. The new owner also owned Hoover Field, and merged the two into a single airfield, Washington-Hoover Airport. Washington-Hoover Airport closed in 1941 when Washington National Airport (now Ronald Reagan Washington National Airport), a replacement facility, was opened.

Hoover Field was an early airport serving the city of Washington, D.C. It was constructed as a private airfield in 1925, but opened to public commercial use on July 16, 1926. It was located in Arlington, Virginia, near the intersection of the Highway Bridge and the Mount Vernon Memorial Parkway, where The Pentagon and its northern parking lots now stand.Considered one of the most hazardous airfields in the United States, Hoover Field suffered from short and unpaved runways, numerous life-threatening obstructions around the field, poor visibility (due to a burning garbage dump to its northwest), and poor drainage. It was purchased by the owner of nearby Washington Airport in early 1929, causing a brief merger of the two fields, but was sold to a new owner just 12 months later. It nearly went bankrupt in 1933, and was sold at auction and merged with Washington Airport to become Washington-Hoover Airport on August 2, 1933. Washington-Hoover Airport closed in June 1941. Washington National Airport (now Ronald Reagan Washington National Airport) was built as its replacement.

Washington-Hoover Airport was an airport serving the city of Washington, D.C., in the United States from 1933 to 1941. It was created by the merger of Hoover Field and Washington Airport on August 2, 1933. It was in Arlington, Virginia, near the intersection of the Highway Bridge and the Mount Vernon Memorial Highway (where The Pentagon and its parking lots now stand). Washington-Hoover Airport, like its predecessors, suffered from safety problems, short runways, and little room to grow. It closed for public use in June 1941, and the United States Department of War purchased the site in September, closing it for good. Washington National Airport (now known as Ronald Reagan Washington National Airport), which opened in June 1941, was built as its replacement. The Pentagon now occupies the site.

The Twin Bridges Motor Hotel, later known as the Twin Bridges Marriott was the first lodging facility operated by what would become Marriott International. It opened on about January 18, 1957, shortly before the second inauguration of President Dwight D. Eisenhower, and was demolished in 1990.

Lyndon Baines Johnson Memorial Grove on the Potomac is located on Columbia Island (renamed Lady Bird Johnson Park in 1968), in Washington, D.C. The presidential memorial honors the 36th President of the United States, Lyndon B. Johnson. The grove consists of two parts. The first area, commemorative in nature, is a Texas granite monolith surrounded by a serpentine pattern of walks and trails. The second area is a grass meadow and provides a tranquil refuge for reflection and rejuvenation of the spirit. The trails are shaded by a grove of hundreds of white pine and dogwood trees, and framed by azaleas and rhododendron. The memorial overlooks the Potomac River with a vista of the city of Washington. Visitors may listen to a recording made by Lady Bird Johnson at the entrance to the park facing The Pentagon. In the recording, the former First Lady talks about the creation of the park, the trees, and the views of major Washington D.C. landmarks.

Air Florida Flight 90 was a scheduled U.S. domestic passenger flight operated by Air Florida from Washington National Airport (now Ronald Reagan Washington National Airport) to Fort Lauderdale–Hollywood International Airport, with an intermediate stopover at Tampa International Airport. On January 13, 1982, the Boeing 737-222 registered as N62AF crashed into the 14th Street Bridge over the Potomac River.Striking the bridge, which carries Interstate 395 between Washington, DC, and Arlington County, Virginia, it hit seven occupied vehicles and destroyed 97 feet (30 m) of guard rail: 5  before plunging through the ice into the Potomac River. The aircraft was carrying 74 passengers and five crew members. Only four passengers and one crew member (a flight attendant) were rescued from the crash and survived. Another passenger, Arland D. Williams, Jr., assisted in the rescue of the survivors, but drowned before he could be rescued. Four motorists on the bridge were killed. The survivors were rescued from the icy river by civilians and professionals. President Ronald Reagan commended these acts during his State of the Union speech a few days later. The National Transportation Safety Board (NTSB) determined that the cause of the accident was pilot error. The pilots failed to switch on the engines' internal ice protection systems, used reverse thrust in a snowstorm prior to takeoff, tried to use the jet exhaust of a plane in front of them to melt their ice, and failed to abandon the takeoff even after detecting a power problem while taxiing and having ice and snow build up on the wings.

Fort Jackson was an American Civil War-era fortification in Virginia that defended the southern end of the Long Bridge, near Washington, D.C. Long Bridge connected Washington, D.C. to Northern Virginia and served as a vital transportation artery for the Union Army during the war. Fort Jackson was named for Jackson City, a seedy suburb of Washington that had been established on the south side of the Long Bridge in 1835. It was built in the days immediately following the Union Army's occupation of Northern Virginia in May 1861. The fort was initially armed with four cannon used to protect the bridge, but these were removed after the completion of the Arlington Line, a line of defenses built to the south. After 1862, the fort lacked weapons except for small arms and consisted of a wooden palisade backed by earthworks. Two cannon were restored to the fort in 1864 following the Battle of Fort Stevens. The garrison consisted of a single company of Union soldiers who inspected traffic crossing the bridge and guarded it from potential saboteurs. Following the final surrender of the Confederate States of America in 1865, Fort Jackson was abandoned. The lumber used in its construction was promptly salvaged for firewood and construction materials and, due to its proximity to the Long Bridge, the earthworks were flattened in order to provide easier access to Long Bridge. In the early 20th century, the fort's site was used for the footings and approaches to several bridges connecting Virginia and Washington. Today, no trace of the fort remains, though the site of the fort is contained within Arlington County's Long Bridge Park, and a National Park Service 2004 survey of the site indicated some archaeological remnants may still remain beneath the park.

Pentagon Army Heliport (ICAO: KJPN, FAA LID: JPN) is a military heliport serving the Pentagon. It consists of a single pentagon-shaped helipad and is located on the northern side of the Pentagon building. It is used for ferrying VIPs such as military leaders and foreign guests to and from the Pentagon by helicopter.

The 14th Street bridges refers to the three bridges near each other that cross the Potomac River, connecting Arlington, Virginia and Washington, D.C. Sometimes the two nearby rail bridges are included as part of the 14th Street bridge complex. A major gateway for automotive, bicycle and rail traffic, the bridge complex is named for 14th Street (U.S. Route 1), which feeds automotive traffic into it on the D.C. end. The complex contains three four-lane automobile bridges — including, from west to east, one southbound, one bi-directional, and one northbound — that carry Interstate 395 (I-395) and U.S. Route 1 (US 1) traffic, as well as a bicycle and pedestrian lane on the southbound bridge. In addition, the complex contains two rail bridges, one of which carries the Yellow Line of the Washington Metro; the other of which, the only mainline rail crossing of the Potomac River to Virginia, carries a CSX Transportation rail line. The five bridges, from west to east are the George Mason Memorial Bridge, the Rochambeau Bridge, the Arland D. Williams, Jr. Memorial Bridge, the Charles R. Fenwick Bridge and the Long Bridge. At the north end of the bridges, in East Potomac Park, the three roadways connect to a pair of two-way bridges over the Washington Channel into downtown Washington, one connecting to traffic (including northbound US 1) north onto 14th Street, and the other connecting to I-395 traffic on the Southwest Freeway. The Metro line connects to a tunnel in the East Potomac Park, and the main line railroad from the Long Bridge passes over I-395 and runs over the Washington Channel just downstream of the 14th Street approach before turning northeast along the line of Maryland Avenue. On January 13, 1982, 78 people were killed when Air Florida Flight 90 clipped the northbound I-395 span of the 14th Street bridge during rush hour and crashed into the Potomac river. The repaired span was renamed in honor of Arland D. Williams Jr., a passenger on the plane who survived the initial crash, but drowned after repeatedly passing a helicopter rescue line to other survivors.

Pentagon Transit Center is a split platform station on the Washington Metro located adjacent to The Pentagon in Arlington, Virginia. The station was opened on July 1, 1977, and is operated by the Washington Metropolitan Area Transit Authority. Providing service for both the Blue and Yellow Lines, the station is where the two lines diverge and thus acts as a transfer point. Northbound, the Blue Line continues through Virginia and the Yellow Line crosses the Potomac River into the District of Columbia. The station opened on July 1, 1977 with the completion of 11.8 miles (19.0 km) of rail between National Airport and RFK Stadium.

The Pentagon is the headquarters building of the United States Department of Defense. It was constructed on an accelerated schedule during World War II. As a symbol of the U.S. military, the phrase The Pentagon is often used as a metonym for the Department of Defense and its leadership. Located in Arlington County, Virginia, across the Potomac River from Washington, D.C., the building was designed by American architect George Bergstrom and built by contractor John McShain. Ground was broken on 11 September 1941, and the building was dedicated on 15 January 1943. General Brehon Somervell provided the major impetus to gain Congressional approval for the project; Colonel Leslie Groves was responsible for overseeing the project for the U.S. Army Corps of Engineers, which supervised it. The Pentagon is the world's largest office building, with about 6.5×10^6 sq ft (150 acres; 60 ha) of floor space, of which 3.7×10^6 sq ft (85 acres; 34 ha) are used as offices. Some 23,000 military and civilian employees, and another 3,000 non-defense support personnel, work in the Pentagon. It has five sides, five floors above ground, two basement levels, and five ring corridors per floor with a total of 17.5 mi (28.2 km) of corridors. The central five-acre (2.0 ha) pentagonal plaza is nicknamed "ground zero" on the presumption that it would be a prime target in a nuclear war.In 2001, the Pentagon was damaged during the September 11 attacks. Five al-Qaeda hijackers flew American Airlines Flight 77 into the western side of the building, killing themselves and 184 others: 59 on the airplane and 125 in the Pentagon. It was the first significant foreign attack on Washington's governmental facilities since the city was burned by the British during the War of 1812. Following the attacks, the western side of the building was repaired, with a small indoor memorial and chapel added at the point of impact. An outdoor memorial dedicated to the Pentagon victims of 9/11 opened in 2008.