It's about one-eightieth as tall as The Singapore Flyer (Ferris wheel)
In other words, 21 hands is 0.0129 times the height of The Singapore Flyer (Ferris wheel), and the height of The Singapore Flyer (Ferris wheel) is 77.50 times that amount.(a.k.a. 新加坡摩天观景轮, a.k.a. சிங்கப்பூர் ஃப்ளையர், a.k.a. Pelayang Singapura) (Marina Centre, Singapore)
The Singapore Flyer has a height of 1,620 hands. Based on recommendations from Feng Shui masters, the wheel was re-engineered to spin in the opposite direction five months after it began operating.
It's about one-eightieth as tall as The Washington Monument
In other words, 21 hands is 0.012603 times the height of The Washington Monument, and the height of The Washington Monument is 79.3460 times that amount.(Washington, D.C.)
The Washington Monument measures 1,666.20 hands tall, with some discrepancy due to the fact that the Monument's base is slightly below the surrounding ground. Interrupted in its construction by the American Civil War, it was almost 36 years between groundbreaking and the completion of construction.
It's about one-eightieth as tall as St. Paul's Cathedral
In other words, 21 hands is 0.0123 times the height of St. Paul's Cathedral, and the height of St. Paul's Cathedral is 81.30 times that amount.(London, England, United Kingdom)
St. Paul's Cathedral measures 1,710 hands to its peak. The southwest tower of the Cathedral contains the bell known as "Great Paul," which is the largest bell in Great Britain at 15,000 kg (16.5 tons), outweighing the more iconic Big Ben bell by about 3,000 kg (3 tons).
It's about one-eighty-fifth as tall as The Space Needle
In other words, the height of The Space Needle is 86.20 times 21 hands.(Seattle, Washington) (to aircraft warning beacon at peak)
Built for a 1962 World's Fair, the Space Needle stands 1,810 hands tall. With a track-and-wheel design inspired by railroad mechanics and a precisely-configured balance, the restaurant near the top of the space needle requires just a 1.5 hp motor to rotate at speeds of about 0.053 kph (0.033 mph).
It's about one-one-hundredth as tall as The Golden Gate Bridge
In other words, 21 hands is 0.0094 times the height of The Golden Gate Bridge, and the height of The Golden Gate Bridge is 106 times that amount.(San Francisco, California and Marin County, California) (height above water)
The height of each tower of Golden Gate Bridge is 2,230 hands above the surface of the San Francisco Bay. One of the key designers of the bridge, Charles Ellis, had no engineering degree when he began working on the project, but would later go on to write what became a standard textbook on structural engineering, and would ultimately be forced to complete his calculations on the bridge by working without pay for five months.
It's about one-one-hundred-fiftieth as long as The QE2
In other words, 21 hands is 0.00726 times the length of The QE2, and the length of The QE2 is 138 times that amount.(a.k.a. RMS Queen Elizabeth 2)
The QE2 has a total length of 2,890 hands. During its voyaging lifetime from 1969 through 2008, it travelled more than 94,500,000,000 hands, the furthest cumulative distance by any ship in modern history.
It's about 150 times as long as an Aspirin
In other words, the length of an Aspirin is 0.0067 times 21 hands.(for up & up aspirin, 325mg, regular strength tablets) (a.k.a. acetylsalicylic acid, a.k.a. ASA)
A single aspirin tablet measures 0.140 hands in diameter. One of the most common medicines in the world and a foundation of worldwide health systems, an estimated 40,000 metric tons of aspirin are consumed each year.