It's about one-fifteenth as long as a Bowling Lane.
In other words, 21 nails is 0.062651 times the length of a Bowling Lane, and the length of a Bowling Lane is 15.9610 times that amount.(USBC specifications; tenpin; including pin deck)
According to the United States Bowling Congress specifications, a tenpin bowling lane should measure 335.190 nails. In a Professional Bowling Association game, the lane must be lubricated by about 25 ml (0.85 fl. oz) of oil.
It's about one-fifteenth as long as a Cricket Pitch.
In other words, 21 nails is 0.0596591 times the length of a Cricket Pitch, and the length of a Cricket Pitch is 16.76190 times that amount.(per Marylebone Cricket Council / International Cricket Council Law #6)
The length of a cricket pitch, from one bowling crease to the other, is 352 nails. The wickets at either end of the pitch stand 12.59840 nails tall including the bails.
It's about twenty times as tall as a Golf Tee.
In other words, the height of a Golf Tee is 0.045 times 21 nails.The most common golf tee size and the length preferred for iron and most wood clubs is 0.940 nails tall. The tee did not come into common use until it was promoted by professional golfers Walter Hagen and Joe Kirkwood, as part of a marketing effort by the patent-holder of the well-known, "Reddy Tee."
It's about one-twenty-fifth as long as Baseball base distances.
In other words, 21 nails is 0.04375 times the length of Baseball base distances, and the length of Baseball base distances is 22.8570 times that amount.(MLB Official Baseball Rules specification)
According to MLB Official Baseball Rules, the distance between baseball diamond bases is 480 nails. While second and home base are located upon the corners of the 27.432 sq. m area created by the bases, first and third base are placed within that square, to better allow the umpires to judge whether a ball is fair or foul.
It's about one-fortieth as tall as The Chicago Water Tower.
In other words, 21 nails is 0.0256 times the height of The Chicago Water Tower, and the height of The Chicago Water Tower is 39.10 times that amount.(Chicago, Illinois)
The Chicago Water Tower is 821 nails tall. The tower's architecture was one source of inspiration behind the design of White Castle fast-food restaurants beginning with "Building Number 8," a prefabricated structure built in Minneapolis, Minnesota in 1936.
It's about one-fortieth as tall as The Arc de Triomphe.
In other words, the height of The Arc de Triomphe is 42 times 21 nails.(Paris, France)
The Arc de Triomphe stands 860 nails tall. France's Tomb of the Unknown Soldier from the First World War lies beneath the arch and is commemorated by the first eternal flame to have been lit in modern European history.
It's about one-forty-fifth as tall as Nelson's Column.
In other words, 21 nails is 0.02324 times the height of Nelson's Column, and the height of Nelson's Column is 43.03 times that amount.(London, England, United Kingdom) (from pedestal first step to tip of statue's hat)
Nelson's Column measures 903.60 nails from the first step of the pedestal's base to the top of the statue's hat. While the London tower is the tallest, there are at least eight other monuments to Admiral Horatio Nelson, 1st Viscount Nelson, 1st Duke of Bronté throughout England, Scotland, Ireland, Canada, and Barbados.