It's about one-and-two-fifths times as long as Hadrian's Wall.
In other words, the length of Hadrian's Wall is 0.71 times 814 furlongs.(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 600 furlongs (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 one-and-two-fifths times as long as The 405.
In other words, 814 furlongs is 1.4051 times the length of The 405, and the length of The 405 is 0.71169 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 579.32 furlongs. 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-and-a-half times as long as The English Channel.
In other words, 814 furlongs is 1.53 times the length of The English Channel, and the length of The English Channel is 0.654 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)
It's about one-and-nine-tenths times as long as The Panama Canal.
In other words, the length of The Panama Canal is 0.53 times 814 furlongs.(Canal de Panamá) (Panama)
It's about two-fifths as long as The Grand Canyon.
In other words, 814 furlongs is 0.367 times the length of The Grand Canyon, and the length of The Grand Canyon is 2.72 times that amount.(a.k.a. Gran Cañón) (Arizona) (Colorado River miles measure)
It's about six times as tall as Olympus Mons.
In other words, 814 furlongs is 6.1 times the height of Olympus Mons, and the height of Olympus Mons is 0.16 times that amount.(a.k.a. Mount Olympus) (Mars)
It's about one-tenth as long as The Rhine.
In other words, 814 furlongs is 0.124 times the length of The Rhine, and the length of The Rhine is 8.06 times that amount.(a.k.a. Rhein, a.k.a. Rijn, a.k.a. Rhin, a.k.a. Rain, a.k.a. Reno, a.k.a. Rhenus, a.k.a. Ryn) (from near Reichenau, Switzerland through Hoek van Holland, Rotterdam, Netherlands)
The Rhine river runs 6,560 furlongs in total length. The World War II Battle of Arnhem, as memorialized in the 1974 book and 1977 movie A Bridge Too Far, was the first of several attempts to capture key bridges across the Rhine, beginning with the Arnhem Bridge in the Netherlands.