How long is 20.5 chains?

The Empire State Building stands 18.940 chains to its architectural peak. The spire emerging from the top of the building was originally intended to be a mooring mast for blimps whose passengers could disembark onto a landing platform on the 102nd floor of the building.

Each of the Petronas Towers stands 22.460 chains to their spires. Holding the record as the tallest buildings in the world from 1998 to 2004, the towers continue to hold the record for the deepest foundation barrettes — up to 5.7170 chains deep.

The Shanghai World Financial Center is 24.50 chains tall to its roof. It is home to both the world's highest hotel (on its 79th through 93rd floors) and the world's tallest observation deck (on its 100th floor, approximately 23.60 chains above ground).

The Willis Tower rises to about 25.80 chains to the top of its tallest antenna. The bathrooms on the 103rd floor are said to be the highest in the western hemisphere at about 20.50 chains.

The Eiffel Tower stands 16.10 chains 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 1.840 chains or less.

The CN Tower measures 27.5060 chains tall at its spire. Used only in emergencies and for charitable climbing events, the 2,579-step staircase to the top is the longest metal staircase in the world.

The QE2 has a total length of 14.60 chains. During its voyaging lifetime from 1969 through 2008, it travelled more than 477,000,000 chains, the furthest cumulative distance by any ship in modern history.

The Guangzhou TV & Sightseeing Tower stands 30 chains to its spire. Initially described as holding the record for the tallest Ferris wheel in the world, the ride at the top of the tower is actually an observation carousel; cars complete a trip around the top-floor track about every half-hour.

The height of each tower of Golden Gate Bridge is 11.30 chains 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.

Gocta Falls, a waterfall on the Cocahuayco River, measures 38.30 chains in total height. Although it sits just 2,090 chains from the major city of Chachapoyas, the waterfall was unknown to non-locals until it was documented during a 2005 expedition by a German economist.

The Navy Pier is 40 chains in total length. Originally named Municipal Pier #2, the pier was renamed Navy Pier in 1927 in honor of Naval personnel stationed there during World War I.

The Three Sisters Falls rise to 40 chains in height. The falls are called Three Sisters after the three large tiers over which the falls flow.

Burj Khalifa, the tallest manmade structure in the world, stands 41.20 chains to its roof. The tower also holds the current records for the world's highest Islamic mosque — at approximately 28.70 chains on the 158th floor (of 163 floors) — and the world's tallest outdoor swimming pool — at approximately 14.20 chains on the 78th floor.

Olo'upena Falls rise to 44.740 chains in height. The isolated falls are the tallest in the United States and the fourth tallest in the world.

Built for a 1962 World's Fair, the Space Needle stands 9.150 chains 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).