It's about one-seventy-thousandth as long as The Panama Canal
In other words, 1,200 milimeters is 0.000014 times the length of The Panama Canal, and the length of The Panama Canal is 71,000 times that amount.(Canal de Panamá) (Panama)
Connecting the Atlantic and Pacific Oceans across the Isthmus of Panama, the Canal measures 88,000,000 milimeters in length. Ships passing through the Canal are raised (and then lowered) 26,000 milimeters above sea level through the lock-and-dam system.
It's about one-ninety-thousandth as wide as The English Channel
In other words, 1,200 milimeters is 0.0000112 times the width of The English Channel, and the width of The English Channel is 89,300 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 107,000,000 milimeters, 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-ninety-five-thousandth as long as The 405
In other words, 1,200 milimeters is 0.000010297 times the length of The 405, and the length of The 405 is 97,116 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 116,540,000 milimeters. 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-one-hundred-thousandth as long as Hadrian's Wall
In other words, 1,200 milimeters is 0.0000100 times the length of Hadrian's Wall, and the length of Hadrian's Wall is 100,000 times that amount.(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 120,000,000 milimeters (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 150,000 times as long as a Red Blood Cell
In other words, 1,200 milimeters is 160,000 times the length of a Red Blood Cell, and the length of a Red Blood Cell is 0.0000063 times that amount.(a.k.a. RBCs, a.k.a. haematids, a.k.a. erythrocyte, a.k.a. erythroid cells, a.k.a. red blood corpuscles)
An average Red Blood Cell measures 7.5 µm (micrometers) in diameter. An average human has 20 - 30 trillion red blood cells in their body and each cell completes a circulatory lap in about 20 seconds.
It's about 200,000 times as long as a Cell's Nucleus
In other words, 1,200 milimeters is 200,000 times the length of a Cell's Nucleus, and the length of a Cell's Nucleus is 0.0000050 times that amount.(for animal cell)
The nucleus of an animal cell measures an average of 0.006 milimeters. The nucleus is the largest organelle in these cells, accounting for about 10% of the cell's total volume.
It's about one-three-hundred-fifty-thousandth as long as The Grand Canyon
In other words, 1,200 milimeters is 0.00000269 times the length of The Grand Canyon, and the length of The Grand Canyon is 372,000 times that amount.(a.k.a. Gran Cañón) (Arizona) (Colorado River miles measure)
The Grand Canyon has a total length of 446,000,000 milimeters along the course of the Colorado River at its bottom. Having opened in early 2007, the Grand Canyon Skywalk allows tourists to stand on a horseshoe-shaped glass walkway 1,100,000 milimeters above the floor of Granite Gorge.