SortStack #3546 — 2036-02-23

By duration · Order from shortest to longest.

1. One full revolution of a helicopter's main rotor 150 ms

   Main rotors spin at only a few hundred rpm, but the blade tips travel so fast they approach the speed of sound — the source of that thudding chop.

2. Usain Bolt's 100 m world record run 9.6 sec

   Bolt ran 9.58 in Berlin 2009, hitting a top speed of 44.7 km/h — faster than the speed limit on many city streets.

3. The construction of the Sydney Opera House 14 years

   Planned as a four-year, $7 million project, it took fourteen years and $102 million — and its architect left Australia before it opened, never returning.

4. The main construction of Notre-Dame de Paris 97 years

   The medieval build ran from 1163 to 1260 — yet after the 2019 fire, the cathedral was restored and reopened in just five years.

5. The era of the Crusades, from the first to the fall of Acre 194.9 years

   Nine major crusades spanned 195 years — and the Fourth never reached the Holy Land at all, sacking Christian Constantinople instead.

6. The Western Roman Empire, from Augustus to its fall 501.9 years

   After the West fell in AD 476, the Eastern half carried on for nearly a thousand more years as the Byzantine Empire.

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