It's about as big as The Lincoln Memorial Reflecting Pool.
It's about three-fifths as big as a Polo field.
In other words, 31.50 dunams is 0.6278947740 times the size of a Polo field, and the size of a Polo field is 1.592623540 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 50.16764160 dunams. 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 three-fifths as big as Windsor Castle.
In other words, 31.50 dunams is 0.590 times the size of Windsor Castle, and the size of Windsor Castle is 1.70 times that amount.(Windsor, England) (total site area)
One of the official residences of the British monarch, Windsor Castle measures about 53 dunams. 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 one-and-nine-tenths times as big as The Kennedy Center.
In other words, the size of The Kennedy Center is 0.530 times 31.50 dunams.(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 17 dunams in total area.
It's about one-and-nine-tenths times as big as The Biltmore Estate.
In other words, 31.50 dunams is 1.930 times the size of The Biltmore Estate, and the size of The Biltmore Estate is 0.5180 times that amount.(Asheville, North Carolina) (house only)
The main house of Biltmore Estate covers 16.30 dunams 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 two times as big as The Great Banyan Tree.
In other words, 31.50 dunams is 2.190 times the size of The Great Banyan Tree, and the size of The Great Banyan Tree is 0.4570 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 14.40 dunams. While its exact age is unknown, the tree has been noted in guidebooks for over 200 years.
It's about two-fifths as big as Buckingham Palace.
In other words, 31.50 dunams is 0.410 times the size of Buckingham Palace, and the size of Buckingham Palace is 2.40 times that amount.(a.k.a. Buckingham House) (Westminster, London, England)
Buckingham Palace, the official residence of the British monarch, contains about 77 dunams 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.