It's about five times as long as a Beetle (Volkswagen)
In other words, 21 meters is 5.148 times the length of a Beetle (Volkswagen), and the length of a Beetle (Volkswagen) is 0.1943 times that amount.(1964 model) (a.k.a. Volkswagen 1200, a.k.a. Käfer)
A 1964 Volkswagen Beetle measures 4.079 m. As the longest continuously-produced automobile design — in production for 75 years between 1938 and 2003 — the Beetle was voted the most fourth-most influential car of the twentieth century by the Global Automotive Elections Foundation.
It's about one-fifth as long as a Football field
In other words, 21 meters is 0.191382 times the length of a Football field, and the length of a Football field is 5.22515 times that amount.(American) (total distance; per NFL regulation)
According to NFL specifications, an American football field should measure 109.7280 meters from end to end. Because each team's goalpost is located at the far end of the scoring area (end zone), a ball on a scoring play may need to travel as many as 9.1440 meters farther when kicked into the scoring area than when run (rushed) or passed into it.
It's about one-fifth as tall as The Great Pyramid of Giza
In other words, 21 meters is 0.16 times the height of The Great Pyramid of Giza, and the height of The Great Pyramid of Giza is 6.3 times that amount.(a.k.a. Pyramid of Khufu, a.k.a. Pyramid of Cheops) (Cairo, Egypt) (estimated original height)
The Great Pyramid of Giza has an estimated original height (without loss due to erosion) of 130 m (280 cubits). The Pyramid was the tallest structure in the world for almost 4,000 years — from its construction ca. 2551 BCE until it was overtaken by the Lincoln Cathedral in Lincoln, England, built in the year 1300.
It's about one-tenth as long as The Shambles
In other words, 21 meters is 0.14 times the length of The Shambles, and the length of The Shambles is 7.1 times that amount.(a.k.a. Maze of Twisting, a.k.a. The Great Flesh Shambles) (York, England, United Kingdom) (approximate)
The Shambles, a historic shopping street in York, stretches about 150 meters. Several of the buildings along the street are over seven hundred years old.
It's about one-tenth as tall as The Spring Temple Buddha
In other words, 21 meters is 0.137 times the height of The Spring Temple Buddha, and the height of The Spring Temple Buddha is 7.3 times that amount.(a.k.a. 中原大佛, a.k.a. 鲁山大佛, a.k.a. 魯山大佛) (Fodushan Scenic Area, Lushan County, Henan, China) (including base)
The tallest statue in the world, the Spring Temple Buddha in Henan, China stands at 153 m tall from its base. The Buddha is located in the 47,300,000-sq. m (11,700-acre) Fodushan Scenic Area near Mount Yao
It's about one-tenth as tall as Blackpool Tower
In other words, 21 meters is 0.133 times the height of Blackpool Tower, and the height of Blackpool Tower is 7.52 times that amount.(Blackpool, Lancashire, England, United Kingdom) (height to peak)
Blackpool Tower, part of an entertainment complex in Blackpool, Lancashire, England, measures 158 m to its peak. Under ideal conditions, visitors to the highest accessible point of the tower can see as far as the Isle of Man — 96,000 meters to the northwest.
It's about one-tenth as long as The Seventeenth hole of Pebble Beach
In other words, 21 meters is 0.13 times the length of The Seventeenth hole of Pebble Beach, and the length of The Seventeenth hole of Pebble Beach is 7.69 times that amount.(fully Pebble Beach Golf Links) (Pebble Beach; Monterey, California) (from Blue Tee)
The seventeenth hole on Pebble Beach Golf Links is a par 3 measuring 162 m from the blue tee. This hole was the site of professional golfer Jack Nicklaus' 1972 U.S. Open win, which included a 1-iron shot that bounced off the hole's flag and resulted in a birdie.