It's about twenty times as long as Hadrian's Wall.
In other words, the length of Hadrian's Wall is 0.042 times 18,700,000 shaftments.(a.k.a. Roman Wall, a.k.a. The Wall, a.k.a. Vallo di Adriano, a.k.a. Vallum Aelium, a.k.a. Severus' Wall) (from North Tyneside, Tyne and Wear, England, United Kingdom to Cumbria, North West England, United Kingdom)
Hadrian's Wall, which crossed England form the North Sea to the Irish Sea during the time of Roman rule, measures 790,000 shaftments (about 79 Roman miles). Roman soldiers — at one time up to 10,000 of them — only occupied Great Britain for about 246 years after the wall was built, after which time the local Brits began to take residence the wall's garrisons.
It's about twenty times as long as The 405.
In other words, 18,700,000 shaftments is 24.4540 times the length of The 405, and the length of The 405 is 0.040893 times that amount.(a.k.a. I-405, Interstate 405, San DIego Freeway) (Southern California)
Running from Irvine to San Fernando, The 405 runs a total of 764,700 shaftments. The 405 is the most heavily-trafficed freeway in the United States, with an average speed as low as 8 kph during rush hours.
It's about thirty times as long as The English Channel.
In other words, 18,700,000 shaftments is 26.60 times the length of The English Channel, and the length of The English Channel is 0.0376 times that amount.(average width between Isle of Ushant and The Walde Lighthouse) (La Manche, Ärmelkanal, Mor Breizh, Mor Bretannek) (a.k.a. The Channel)
The English Channel measures between 702,000 shaftments, narrowing as it flows northeast. The world speed record for a Channel crossing by swimmer was set by Australian Trent Grimsey in 2012, with a time of 6 hours, 55 minutes.
It's about thirty times as long as The Panama Canal.
In other words, the length of The Panama Canal is 0.031 times 18,700,000 shaftments.(Canal de Panamá) (Panama)
Connecting the Atlantic and Pacific Oceans across the Isthmus of Panama, the Canal measures 580,000 shaftments in length. Ships passing through the Canal are raised (and then lowered) 170 shaftments above sea level through the lock-and-dam system.
It's about 100 times as tall as Olympus Mons.
In other words, 18,700,000 shaftments is 110 times the height of Olympus Mons, and the height of Olympus Mons is 0.0091 times that amount.(a.k.a. Mount Olympus) (Mars)
The tallest mountain in the solar system, Olympus Mons rises to approximately 180,000 shaftments. The mountain has been known to astronomers since the nineteenth century because it is tall enough to rise above Mars' frequent dust storms.
It's about one-one-hundred-fiftieth as long as The Distance from Earth to the Moon.
In other words, 18,700,000 shaftments is 0.007413136 times the length of The Distance from Earth to the Moon, and the length of The Distance from Earth to the Moon is 134.89570 times that amount.(a.k.a. Luna) (median of semi-major axis, or apigee, and semi-minor axes, or perigee)
The orbit of the Moon around the Earth is elliptical, with an average distance of 2,522,549,000 shaftments from center-to-center. About 428.376 kg of moon rock have been cataloged on the Earth, from the American Apollo and Soviet Luna Programs, and from samples that have been extracted from meteorites.
It's about 250 times as tall as Maxwell Montes.
In other words, the height of Maxwell Montes is 0.0038 times 18,700,000 shaftments.(Ishtar Terra, Venus)
Maxwell Montes rises to a total height of 72,000 shaftments. Since Venus does not seem to have the kind of tectonic activity which gives rise to mountains on Earth, the origin of the Venusian mountain remains the subject of some dispute.