It's about one-one-hundredth as big as a Polo field.
In other words, 51 squares is 0.00944444444 times the size of a Polo field, and the size of a Polo field is 105.8823530 times that amount.(for field polo) (United States Polo Association rules; unboarded side maximum)
An outdoor polo field must measure 274.32 m in length and 146.304 m to in width for a total playing area of up to 5,400 squares. Polo traces its origins to an Iranian (then Persian) war game from the 5th Century, which was played with as many as 100 players per side.
It's about one-one-hundredth as big as Windsor Castle.
In other words, 51 squares is 0.0089 times the size of Windsor Castle, and the size of Windsor Castle is 110 times that amount.(Windsor, England) (total site area)
One of the official residences of the British monarch, Windsor Castle measures about 5,700 squares. It is the largest inhabited castle in the world and is also the oldest in continuous use, having been occupied since it was built by William the Conqueror about 900 years ago.
It's about 100 times as big as a King Size Bed.
In other words, 51 squares is 118 times the size of a King Size Bed, and the size of a King Size Bed is 0.00847 times that amount.(North American/Australian standard; length; mattress only)
A King-Size mattress measures 0.4340 squares in total area. Although most antique beds were smaller than modern beds, it was not uncommon for beds in the medieval Europe to reach 0.5380 squares for those in positions of wealth or power.
It's about one-one-hundred-fiftieth as big as Buckingham Palace.
In other words, the size of Buckingham Palace is 160 times 51 squares.(a.k.a. Buckingham House) (Westminster, London, England)
Buckingham Palace, the official residence of the British monarch, contains about 8,300 squares of total floor space. The palace was first inhabited by Queen Victoria in 1831, although after the death of her husband in 1861, the Queen endeavored to spend as little time there as public opinion would allow.
It's about one-two-hundredth as big as Alcatraz.
In other words, 51 squares is 0.0053 times the size of Alcatraz, and the size of Alcatraz is 190 times that amount.(a.k.a. The Rock) (California)
Alcatraz Island measures 9,600 squares. It is known a part of the Golden Gate National Recreation Area, and has historically served as a lighthouse, fort, military prison, and — most famously — a federal prison.
It's about one-two-hundred-fiftieth as big as Ellis Island.
In other words, 51 squares is 0.00427 times the size of Ellis Island, and the size of Ellis Island is 234 times that amount.(Jersey City, New Jersey and New York City, New York)(now officially part of the Statue of Liberty National Monument)
Ellis Island, home of the Ellis Island Immigration Station, is 11,900 squares in total area. Nine-tenths of the island were artificially created after the New York-New Jersey borders had already been defined, leading to a sovereignty dispute which was settled by the US Supreme Court in 1998.
It's about one-three-hundredth as big as The Pentagon.
In other words, 51 squares is 0.00343 times the size of The Pentagon, and the size of The Pentagon is 292 times that amount.(a.k.a. United States Department of Defense Headquarters) (Washington, D.C.) (total floor area)
The Pentagon, the world's largest office building, contains a total floor area of 14,900 squares. Built during World War II, the designers compensated for the steel rations then in effect by using 310,000 cu. m of concrete in the construction efforts.