It's about as tall as The Spring Temple Buddha.
In other words, the height of The Spring Temple Buddha is 1.04 times 644.10 spans.(a.k.a. 中原大佛, a.k.a. 鲁山大佛, a.k.a. 魯山大佛) (Fodushan Scenic Area, Lushan County, Henan, China) (including base)
The tallest statue in the world, the Spring Temple Buddha in Henan, China stands at 669 spans tall from its base. The Buddha is located in the 47,300,000-sq. m (11,700-acre) Fodushan Scenic Area near Mount Yao
It's about nine-tenths as tall as Blackpool Tower.
In other words, 644.10 spans is 0.9320 times the height of Blackpool Tower, and the height of Blackpool Tower is 1.07 times that amount.(Blackpool, Lancashire, England, United Kingdom) (height to peak)
Blackpool Tower, part of an entertainment complex in Blackpool, Lancashire, England, measures 691 spans to its peak. Under ideal conditions, visitors to the highest accessible point of the tower can see as far as the Isle of Man — 420,000 spans to the northwest.
It's about one-and-one-tenth times as tall as The Great Pyramid of Giza.
In other words, the height of The Great Pyramid of Giza is 0.910 times 644.10 spans.(a.k.a. Pyramid of Khufu, a.k.a. Pyramid of Cheops) (Cairo, Egypt) (estimated original height)
The Great Pyramid of Giza has an estimated original height (without loss due to erosion) of 570 spans. The Pyramid was the tallest structure in the world for almost 4,000 years — from its construction ca. 2551 BCE until it was overtaken by the Lincoln Cathedral in Lincoln, England, built in the year 1300.
It's about nine-tenths as long as The Seventeenth hole of Pebble Beach.
In other words, 644.10 spans is 0.9090 times the length of The Seventeenth hole of Pebble Beach, and the length of The Seventeenth hole of Pebble Beach is 1.10 times that amount.(fully Pebble Beach Golf Links) (Pebble Beach; Monterey, California) (from Blue Tee)
The seventeenth hole on Pebble Beach Golf Links is a par 3 measuring 709 spans from the blue tee. This hole was the site of professional golfer Jack Nicklaus' 1972 U.S. Open win, which included a 1-iron shot that bounced off the hole's flag and resulted in a birdie.
It's about nine-tenths as tall as The Singapore Flyer (Ferris wheel).
In other words, 644.10 spans is 0.8920 times the height of The Singapore Flyer (Ferris wheel), and the height of The Singapore Flyer (Ferris wheel) is 1.120 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 722 spans. Based on recommendations from Feng Shui masters, the wheel was re-engineered to spin in the opposite direction five months after it began operating.
It's about nine-tenths as tall as The Washington Monument.
In other words, 644.10 spans is 0.869760 times the height of The Washington Monument, and the height of The Washington Monument is 1.14970 times that amount.(Washington, D.C.)
The Washington Monument measures 740.550 spans 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 four-fifths as tall as St. Paul's Cathedral.
In other words, 644.10 spans is 0.8460 times the height of St. Paul's Cathedral, and the height of St. Paul's Cathedral is 1.180 times that amount.(London, England, United Kingdom)
St. Paul's Cathedral measures 761 spans 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).