It's about five-and-a-half times as long as The Preakness Stakes.
In other words, 400 shackles is 5.7416270 times the length of The Preakness Stakes, and the length of The Preakness Stakes is 0.17416670 times that amount.(Pimlico Race Course, Baltimore, Maryland) (total race length)
The total race length of the Preakness Stakes run at the Pimlico Race Course is 69.666670 shackles. Dubbed "the race for the Black-eyed Susans" after Maryland's state flower, the winning horse is actually draped with a garland of painted yellow daisies, as Black-eyed Susans do not bloom in time for the late-May race.
It's about one-tenth as long as The Panama Canal.
In other words, 400 shackles is 0.120 times the length of The Panama Canal, and the length of The Panama Canal is 8.30 times that amount.(Canal de Panamá) (Panama)
Connecting the Atlantic and Pacific Oceans across the Isthmus of Panama, the Canal measures 3,200 shackles in length. Ships passing through the Canal are raised (and then lowered) 0.950 shackles above sea level through the lock-and-dam system.
It's about one-tenth as long as The English Channel.
In other words, 400 shackles is 0.1030 times the length of The English Channel, and the length of The English Channel is 9.710 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 3,900 shackles, 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 ten times as long as The Navy Pier.
In other words, the length of The Navy Pier is 0.10 times 400 shackles.(a.k.a. Municipal Pier #2) (Chicago, Illinois)
The Navy Pier is 30 shackles in total length. Originally named Municipal Pier #2, the pier was renamed Navy Pier in 1927 in honor of Naval personnel stationed there during World War I.
It's about ten times as tall as The Three Sisters Falls.
In other words, the height of The Three Sisters Falls is 0.10 times 400 shackles.(a.k.a. Cataratas las Tres Hermanas) (Ayacucho, Peru)
The Three Sisters Falls rise to 30 shackles in height. The falls are called Three Sisters after the three large tiers over which the falls flow.
It's about one-tenth as long as The 405.
In other words, 400 shackles is 0.094155 times the length of The 405, and the length of The 405 is 10.6210 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 4,248.40 shackles. 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-tenth as long as Hadrian's Wall.
In other words, the length of Hadrian's Wall is 11 times 400 shackles.(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 4,400 shackles (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.