It's about 0.0000005 times as long as Hadrian's Wall
In other words, 2.10 inches is 0.00000044 times the length of Hadrian's Wall, and the length of Hadrian's Wall is 2,300,000 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 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.
It's about 0.0000001 times as long as The Grand Canyon
In other words, 2.10 inches is 0.00000012 times the length of The Grand Canyon, and the length of The Grand Canyon is 8,330,000 times that amount.(a.k.a. Gran Cañón) (Arizona) (Colorado River miles measure)
The Grand Canyon has a total length of 17,600,000 inches 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 43,300 inches above the floor of Granite Gorge.
It's about 0.00000004 times as long as The Rhine
In other words, 2.10 inches is 0.0000000404 times the length of The Rhine, and the length of The Rhine is 24,800,000 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 52,000,000 inches 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.
It's about 35,000,000 times as wide as a Glucose Molecule
In other words, 2.10 inches is 36,000,000 times the width of a Glucose Molecule, and the width of a Glucose Molecule is 0.000000028 times that amount.(C6H12O6, a.k.a. grape sugar) (open chain form)
Am individual glucose molecule measures 0.0000000590 inches in its open-chain form. Glucose is the most common fuel source of energy in human biology, with 3.75 kilocalories of energy per gram.
It's about 0.00000003 times as long as The Colorado River
In other words, 2.10 inches is 0.0000000229 times the length of The Colorado River, and the length of The Colorado River is 43,700,000 times that amount.(a.k.a. Aha Kwahwat, a.k.a. Grand River, a.k.a. Tizon River, a.k.a. Tecon River, a.k.a. Tison River) (from Grand Lake, Colorado through the Gulf of California)
The Colorado River runs 91,700,000 inches in length. Along this length, the river descends from its source, approximately 108,000 inches above sea level in the Rocky Mountains, to its mouth in the Gulf of California.
It's about 0.00000002 times as long as The Danube
In other words, 2.10 inches is 0.0000000187 times the length of The Danube, and the length of The Danube is 53,500,000 times that amount.(a.k.a. Donau, a.k.a. Dunaj, a.k.a. Dunav, a.k.a. Duna, a.k.a. Дунав (Dunav), a.k.a. Dunărea, a.k.a. Дунáй (Dunay), a.k.a. Tuna) (from Breg Martinskapelle, Black Forest, Germany through the Danube Delta, Romania)
The Danube river runs 112,000,000 inches in total length. Intersecting Vienna, Austria; Bratislava, Slovakia; Budapest, Hungary; and Belgrade, Serbia, the Danube touches more capital cities than any other river.
It's about 0.00000002 times as long as The Oregon Trail
In other words, 2.10 inches is 0.0000000153 times the length of The Oregon Trail, and the length of The Oregon Trail is 65,400,000 times that amount.(from Independence, Missouri to Oregon City, Oregon)
The historic Oregon Trail stretched 137,000,000 inches across five (sometimes six) states in the western United States. In the early years of the Trail's existence, the trip was estimated to have taken an average of 160 days.