It's about 3,000 times as long as a Strand of Spaghetti (thickness).
In other words, 216 inches is 3,200 times the length of a Strand of Spaghetti (thickness), and the length of a Strand of Spaghetti (thickness) is 0.00031 times that amount.(average; restaurant and supermarket applications) (based on FMA Omcan Italian Made TR50 Counter Top Pasta Machine Extruder 13317)
An average strand of restaurant-grade spaghetti measures 0.067 inches in thickness. In 2010, a California Buca di Beppo set a world record by preparing a 13,780-lb bowl of spaghetti, served in a swimming pool.
It's about 4,500 times as long as a Grain of Sand.
In other words, 216 inches is 4,390 times the length of a Grain of Sand, and the length of a Grain of Sand is 0.000228 times that amount.(medium grain)
Composed mainly of quartz, mica, feldspar, or magnetite, a grain of sand measures an average of 0.0492 inches. In 2007, a team of seven in Myrtle Beach created the world's tallest sandcastle, which measured 594 inches in height.
It's about one-five-thousandth as tall as Olympus Mons.
In other words, the height of Olympus Mons is 5,000 times 216 inches.(a.k.a. Mount Olympus) (Mars)
The tallest mountain in the solar system, Olympus Mons rises to approximately 1,100,000 inches. 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-fifteen-thousandth as long as The Panama Canal.
In other words, the length of The Panama Canal is 16,000 times 216 inches.(Canal de Panamá) (Panama)
Connecting the Atlantic and Pacific Oceans across the Isthmus of Panama, the Canal measures 3,500,000 inches in length. Ships passing through the Canal are raised (and then lowered) 1,000 inches above sea level through the lock-and-dam system.
It's about one-twenty-thousandth as long as The English Channel.
In other words, 216 inches is 0.00005130 times the length of The English Channel, and the length of The English Channel is 19,500 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 4,210,000 inches, 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 one-twenty-thousandth as long as The 405.
In other words, 216 inches is 0.0000470770 times the length of The 405, and the length of The 405 is 21,242 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 4,588,200 inches. 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 one-twenty-thousandth as long as Hadrian's Wall.
In other words, the length of Hadrian's Wall is 22,000 times 216 inches.(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 4,700,000 inches (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.