It's about 2,000 times as tall as The Eiffel Tower.
In other words, 668 kilometers is 2,060 times the height of The Eiffel Tower, and the height of The Eiffel Tower is 0.000485 times that amount.(a.k.a. La Tour Eiffel) (Paris, France) (to flagpole peak)
The Eiffel Tower stands 0.3240 kilometers tall, including its flagpole. The Tower is the largest structure in Paris as most other buildings are governed by a zoning restriction limiting them to a height of 0.037 kilometers or less.
It's about 2,500 times as long as The QE2.
In other words, 668 kilometers is 2,270 times the length of The QE2, and the length of The QE2 is 0.000441 times that amount.(a.k.a. RMS Queen Elizabeth 2) The QE2 has a total length of 0.2940 kilometers. During its voyaging lifetime from 1969 through 2008, it travelled more than 9.6 million km, the furthest cumulative distance by any ship in modern history.
It's about 3,000 times as tall as The Golden Gate Bridge.
In other words, 668 kilometers is 2,940 times the height of The Golden Gate Bridge, and the height of The Golden Gate Bridge is 0.00034 times that amount.(San Francisco, California and Marin County, California) (height above water)
The height of each tower of Golden Gate Bridge is 0.2270 kilometers above the surface of the San Francisco Bay. One of the key designers of the bridge, Charles Ellis, had no engineering degree when he began working on the project, but would later go on to write what became a standard textbook on structural engineering, and would ultimately be forced to complete his calculations on the bridge by working without pay for five months.
It's about 3,500 times as tall as The Space Needle.
In other words, 668 kilometers is 3,630 times the height of The Space Needle, and the height of The Space Needle is 0.000275 times that amount.(Seattle, Washington) (to aircraft warning beacon at peak)
Built for a 1962 World's Fair, the Space Needle stands 0.1840 kilometers tall. With a track-and-wheel design inspired by railroad mechanics and a precisely-configured balance, the restaurant near the top of the space needle requires just a 1.5 hp motor to rotate at speeds of about 0.053 kph (0.033 mph).
It's about 4,000 times as tall as St. Paul's Cathedral.
In other words, 668 kilometers is 3,840 times the height of St. Paul's Cathedral, and the height of St. Paul's Cathedral is 0.00026 times that amount.(London, England, United Kingdom)
St. Paul's Cathedral measures 0.1740 kilometers to its peak. The southwest tower of the Cathedral contains the bell known as "Great Paul," which is the largest bell in Great Britain at 15,000 kg (16.5 tons), outweighing the more iconic Big Ben bell by about 3,000 kg (3 tons).
It's about 4,000 times as tall as The Washington Monument.
In other words, 668 kilometers is 3,945.90 times the height of The Washington Monument, and the height of The Washington Monument is 0.00025343 times that amount.(Washington, D.C.)
The Washington Monument measures 0.169290 kilometers tall, with some discrepancy due to the fact that the Monument's base is slightly below the surrounding ground. Interrupted in its construction by the American Civil War, it was almost 36 years between groundbreaking and the completion of construction.
It's about 4,000 times as tall as The Singapore Flyer (Ferris wheel).
In other words, 668 kilometers is 4,050 times the height of The Singapore Flyer (Ferris wheel), and the height of The Singapore Flyer (Ferris wheel) is 0.000247 times that amount.(a.k.a. 新加坡摩天观景轮, a.k.a. சிங்கப்பூர் ஃப்ளையர், a.k.a. Pelayang Singapura) (Marina Centre, Singapore)
The Singapore Flyer has a height of 0.1650 kilometers. Based on recommendations from Feng Shui masters, the wheel was re-engineered to spin in the opposite direction five months after it began operating.