It's about one-fifteenth as big as The White House.
In other words, the size of The White House is 13 times 51 squares.(Washington, DC) (including wings)
Housing the presidency, the White House occupies six stories and a total of 670 squares of floor space. This space includes 132 rooms, 35 bathrooms, 28 fireplaces, and 3 elevators, as well as a tennis court, bowling alley, movie theater, jogging track, swimming pool, and putting green.
It's about one-twentieth as big as a City Block (Manhattan).
In other words, the size of a City Block (Manhattan) is 20 times 51 squares.(per Bridges, William - 1811 Commissioner's Plan for New York City) (approximate)
A Manhattan city block measures about 200 m between the Northeast-Southwest streets by about 60 m between the Northwest-Southeast streets for a total area of about 1,000 squares. There are roughly 2,000 blocks within the city, representing one of the most prolific applications of the city planning grid plan in history.
It's about one-thirtieth as big as The Great Banyan Tree.
In other words, 51 squares is 0.0329 times the size of The Great Banyan Tree, and the size of The Great Banyan Tree is 30.40 times that amount.(a.k.a. The Great Banyan, a.k.a. Ficus benghalensis) (Acharya Jagadish Chandra Bose Indian Botanic Garden, Howrah, West Bengal, India)
The Great Banyan Tree is a single tree in the Indian Botanic Garden in West Bengal with aerial roots covering a total area of about 1,550 squares. While its exact age is unknown, the tree has been noted in guidebooks for over 200 years.
It's about thirty times as big as a Parking Space.
In other words, 51 squares is 31.60 times the size of a Parking Space, and the size of a Parking Space is 0.0316 times that amount.(a.k.a Parking Stall) (average; surface lot; North America)
An average-size parking space in a North American surface lot measures 1.610 squares. Due to the high real estate prices at the time, parking spaces in a densely-populated part of Manhattan would sell for an average of $165,000 in 2007, with some spaces fetching up to $225,000.
It's about one-thirty-fifth as big as The Biltmore Estate.
In other words, the size of The Biltmore Estate is 34.40 times 51 squares.(Asheville, North Carolina) (house only)
The main house of Biltmore Estate covers 1,750 squares and contains 250 rooms. The fifty-six auxiliary buildings of the estate are interconnected through the nearly 71 km of roads on the Biltmore grounds.
It's about one-thirty-fifth as big as The Kennedy Center.
In other words, the size of The Kennedy Center is 36 times 51 squares.(a.k.a. John F. Kennedy Memorial Center for the Performing Arts) (Washington, DC)
Hosting over 2,000 performances and nearly two million audience members annually — including events and guests for presidential inaugurations and galas — the Kennedy Center is approximately 1,800 squares in total area.
It's about one-sixty-fifth as big as The Lincoln Memorial Reflecting Pool.