It's about one-tenth as tall as The Singapore Flyer (Ferris wheel)
In other words, 21 meters is 0.1270 times the height of The Singapore Flyer (Ferris wheel), and the height of The Singapore Flyer (Ferris wheel) is 7.870 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 165 m. 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-tenth as tall as The Washington Monument
In other words, 21 meters is 0.124050 times the height of The Washington Monument, and the height of The Washington Monument is 8.0613 times that amount.(Washington, D.C.)
The Washington Monument measures 169.29 m 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-tenth as tall as St. Paul's Cathedral
In other words, 21 meters is 0.1210 times the height of St. Paul's Cathedral, and the height of St. Paul's Cathedral is 8.260 times that amount.(London, England, United Kingdom)
St. Paul's Cathedral measures 174 m 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-tenth as tall as The Space Needle
In other words, 21 meters is 0.1140 times the height of The Space Needle, and the height of The Space Needle is 8.770 times that amount.(Seattle, Washington) (to aircraft warning beacon at peak)
Built for a 1962 World's Fair, the Space Needle stands 184 m 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 nine times as tall as a Christmas Tree (artificial)
In other words, 21 meters is 9.10 times the height of a Christmas Tree (artificial), and the height of a Christmas Tree (artificial) is 0.110 times that amount.(artificial; average height)
The most common height of an artificial Christmas Tree is 2.3 m. According to the most recent USDA Census of Agriculture, a total of 1,389.59 sq. km (343,374 acres) of Christmas Trees were farmed in the US in 2007.
To all those observing, Merry Christmas from The Measure of Things!
It's about nine-and-a-half times as tall as André the Giant
In other words, the height of André the Giant is 0.110 times 21 meters.(Andr( Ren( Ruossimoff) (1946-1993) (wrestler and actor; WWE kayfabe height)
Andr& the Giant, who had a pituitary syndrome called acromegaly, was 2.2 m tall. Prior to 1973, Roussimoff was billed as having a height of 2.1 m and his true height is the subject of some dispute.
It's about nine-and-a-half times as tall as Shaq
In other words, the height of Shaq is 0.110 times 21 meters.(Shaquille O'Neal) (1972-) (professional basketball player, most famously of the Los Angeles Lakers)
Shaq is 2.2 m tall. Shaq maintains an active interest in police work and has served as a reserve officer in both Los Angeles, California and Miami, Florida while playing for NBA franchises in those cities.