Question: How large is the memorial that forms the boundary of Constitution Gardens on the west  ?

Context paragraphs:
Dehiwala-Mount Lavinia: Dehiwala-Mount Lavinia (Sinhalese: දෙහිවල-ගල්කිස්ස "Dehiwala-Galkissa", Tamil: தெஹிவளை-கல்கிசை ), population 245,974 (2012) is the second largest Municipality in Sri Lanka, and covers an extent of 2109 hectares.  It lies south of the Colombo Municipal Council area and separated from it by the Dehiwala canal which forms the northern boundary of DMMC.  Its southern limits lie in Borupana Road and the eastern boundary is Weras Ganga with its canal system and including some areas to its east (Pepiliyana, Gangodawila and Kohuwala).  This town has extensive population and rapid industrialization and urbanization in recent years.  It is home to Sri Lanka's National Zoological Gardens, which remains one of Asia's largest.  Colombo South Teaching Hospital, Kalubowila and Colombo Airport, Ratmalana are some important landmark in this area.  Dehiwela-Mount Lavinia and Sri Jayawardenapura Kotte being two large suburban centers of the city of Colombo function together as one large urban agglomeration in the Region (Western Province).  The overspill from the City in residential and commercial uses of land have rapidly urbanized these suburban centers.  Dehiwela-Mount Lavinia and Sri Jayawardenpaura along with Colombo Municipal Council form the most urbanized part of the core area of the Colombo Metropolitan Region.  Dehiwala and Mount Lavinia lie along the Galle Road artery, which runs along the coast to the south of the country.

Fanshawe College Arboretum: The Gardens of Fanshawe College were started in 1995 when St. Pauls Cathedral was looking for land within London, Ontario to create a memorial garden of tree plantings in the names of deceased Londoners.  They approached Fanshawe College after locating a large expanse of vacant land in the area.  Subsequently, after discussions concerning upkeep and possible vandalism, Fanshawe set aside an area now known as Woodland Gardens in 1995.  An organized and accessioned garden was begun after this time and the Spriet Family Greenhouse was added to the Horticulture Technician Program.  The gardens have now evolved into The Gardens of Fanshawe College which also include The A. M. Mac Cuddy Gardens, some forty minutes west of London north of the town of Strathroy.

McKenzie Mountain Wilderness Area: The McKenzie Mountain Wilderness Area, an Adirondack Park unit of the Forest Preserve, lies in western Essex County in the towns of St. Armand, North Elba and Wilmington.  In general, the Saranac River and Franklin Falls Pond border on the north; the Wilmington-Franklin Falls road, the Whiteface Mountain Memorial Highway and the west branch of the Ausable River form the eastern boundary; the Saranac Lake-Lake Placid Road, NY 86, forms the southern boundary; and the Saranac River forms the western boundary.

Constitution Gardens: Constitution Gardens is a park area in Washington, D.C., United States, located within the boundaries of the National Mall.  The 50 acre park is bounded on the west by the Vietnam Veterans Memorial, on the east by 17th St NW, on the north by Constitution Avenue, and on the south by the Reflecting Pool.  Constitution Gardens has a small pond, which contains an island open to pedestrians.

Ripps Island: Ripps Island was an island located in the Potomac River in the northwest quadrant of Washington, D.C., in the United States.  It was located at the mouth of Tiber Creek, in the vicinity of today's Constitution Gardens.

Vietnam Veterans Memorial: The Vietnam Veterans Memorial is a 2-acre (8,000 m²) national memorial in Washington, D.C. It honors U.S. service members of the U.S. armed forces who fought in the Vietnam War, service members who died in service in Vietnam/South East Asia, and those service members who were unaccounted for (missing in action, MIA) during the war.

Dwight Watson (farmer): Dwight Ware Watson (born September 28, 1952), dubbed the "Tractor Man" in the media, is a tobacco farmer from Whitakers, North Carolina, who brought much of Washington, D.C. to a standstill for two days when he drove a tractor into the pond in the Constitution Gardens area of the National Mall and claimed to have explosives.  The standoff with federal and local law enforcement ended when Watson surrendered.  He was subsequently convicted in federal court of making a false threat to detonate explosives and for destroying federal property, and served 16 months in prison.

North Tabor, Portland, Oregon: North Tabor Neighborhood in Portland, Oregon, United States, is on the east side of the Willamette River on the northern slope of Mount Tabor.  The Banfield Expressway (Interstate 84) forms its northern boundary, separating it from the Hollywood District, Rose City Park, and Madison South neighborhoods to the north.  NE/SE 44th Ave. separates it from Laurelhurst to the west and NE 68th Ave. from Montavilla to the east.  East Burnside Street forms most of the southern boundary (separating it from the Mount Tabor Neighborhood), except for a section west of SE 49th Ave. for which SE Stark St. forms the boundary with the Sunnyside neighborhood.

Cathays (electoral ward): The Cathays ( ) electoral ward of Cardiff consists of some or all of the following areas: Blackweir, Cardiff city centre, Cathays, Cathays Park and Maindy in the parliamentary constituency of Cardiff Central.  It is bounded by Gabalfa and Birchgrove to the north; Plasnewydd and Adamsdown to the east; Butetown to the south; and Riverside to the west.  The River Taff forms its western boundary to where it meets the South Wales Main Line, the South Wales Main Line forms the southern boundary to where it meets the Valley Lines northbound branch, this railway line then forms the eastern boundary as far as the A48 road.  The Northern boundary follows the A48 as far as Allensbank Road where it follows this road south then turns north again along Whitchurch Road.  It turns west along Crown Way, then south along the A470 until North Road where it bears west, passing just south of the student halls, until it meets the River Taff.  The tallest building in Wales is here and is also part of the Cardiff's CBD.

March 17, 2007 anti-war protest: The March 17, 2007 anti-war protest was an anti-war demonstration sponsored by ANSWER Coalition that marched from Constitution Gardens in Washington, D.C. to The Pentagon in Arlington, Virginia.  The date was selected to coincide with the fourth anniversary of the invasion of Iraq, and also the 40th anniversary of a similar anti-war march on October 21, 1967.  Organizers estimated 15,000 to 30,000 protesters attended, while the police gave informal estimates of 10,000 to 20,000.

Supporting paragraphs: Constitution Gardens Vietnam Veterans Memorial
Answer: 2-acre (8,000 m²)