It's about 100 times as tall as Mount Elbrus.
In other words, 668 kilometers is 118.40 times the height of Mount Elbrus, and the height of Mount Elbrus is 0.008446 times that amount.(a.k.a. Mingi Tau, a.k.a. Эльбрус, a.k.a. იალბუზი) (Karachay-Cherkessia and Kabardino-Balkaria, Russia) (west summit)
The west summit of the dual-summit volcano Mount Elbrus is 5.6420 kilometers at its peak and is the highest peak in both Russia and the European continent. Until 1976, a cable car would take visitors to the mountain as far up as the Garabashi camp, located at an elevation of 3.80 kilometers.
It's about 150 times as tall as a Vinson Massif.
In other words, 668 kilometers is 136.50 times the height of a Vinson Massif, and the height of a Vinson Massif is 0.007326 times that amount.(a.k.a. Mount Vinson) (Antarctica)
Mount Vinson, the highest peak of the Vinson Massif mountain, reaches 4.8920 kilometers at its peak. The mountain is named after Georgia Congressman Carl Vinson who emphatically promoted Antarctic exploration in the 1930s.
It's about 150 times as tall as a Puncak Jaya.
In other words, 668 kilometers is 136.80 times the height of a Puncak Jaya, and the height of a Puncak Jaya is 0.00731 times that amount.(a.k.a. Mt. Carstensz, a.k.a. Carstensz Pyramid, a.k.a. Nemangkawi, a.k.a. Carstensz Toppen, a.k.a. Gunung Sukarno) (Papua province, Indonesia)
The highest point in Oceania (and therefore one of the seven summits) peak of Puncak Jaya is 4.8840 kilometers. Dutch explorer Jan Carstenszoon, the mountain's namesake, is said to have been ridiculed for claiming to have seen snow near the equator when he reported his discovery of the peak in 1623.
It's about 150 times as long as The Indianapolis Motor Speedway.
In other words, 668 kilometers is 166.03 times the length of The Indianapolis Motor Speedway, and the length of The Indianapolis Motor Speedway is 0.00602301 times that amount.(Speedway, Indiana) (rectangular oval course)
The rectangular oval course of the Indianapolis Motor Speedway is 4.02336 km. While famous for its automotive racing, the first motorsport held at the track was a series of motorcycle races in August, 1909 — a little less than two years before the inaugural Indianapolis 500 race was run.
It's about 150 times as long as Daytona International Speedway.
In other words, 668 kilometers is 166.03 times the length of Daytona International Speedway, and the length of Daytona International Speedway is 0.00602301 times that amount.(Daytona Beach, Florida) (tri-oval course)
The tri-oval course of the Daytona International Speedway, upon which the NASCAR Daytona 500 is run, is 4.02336 km in length. Although the tri-oval design is said to allow for greater visibility during the race, the real reason for the then-unique design was that plot available for construction of the track was only 350 acres and could not accommodate a traditional oval layout of appropriate length.
It's about 150 times as long as The Hollywood Walk of Fame.
In other words, the length of The Hollywood Walk of Fame is 0.0059 times 668 kilometers.(Hollywood Boulevard and Vine Street, Hollywood, California) (approximate length)
The Hollywood Walk of Fame is approximately 3.9 km. Gene Autry, most famous as the singer of "Back in the Saddle Again" and as the writer and singer of "Here Comes Santa Claus," is the only entertainer to have a star in every category — film, television, recording, radio, and theater. One of Autry's stars is also one of only two stars which have been stolen from the Walk and never recovered.
It's about 200 times as long as The National Mall.
In other words, the length of The National Mall is 0.005 times 668 kilometers.(Washington, D.C.) (to Lincoln Memorial)
From the steps of the Capitol Building to the Lincoln Memorial, the National Mall is 3.0 km. On December 4th, 2008, the entirety of the Mall was declared open to the public for the first time in American history in anticipation of the estimated two million visitors to the Mall for the inauguration of President Barack Obama on January 20th, 2009.