“A monowheel is a one-wheeled single-track vehicle similar to a unicycle. However, instead of sitting above the wheel, the rider sits either within it or next to it. The wheel is a ring, usually driven by smaller wheels pressing against its inner rim. Most are single-passenger vehicles, though multi-passenger models have been built.

Pedal-powered monowheels were built in the late 19th century; most built in the 20th century have been motorized. Some modern builders refer to these vehicles as monocycles, though that term is also sometimes used to describe motorized unicycles. Today, monowheels are generally built and used for fun and entertainment purposes, though from the 1860s through to the 1930s, they were proposed for use as serious transportation”. – Wikipedia

Photo: Cycle inventor Kerry McLean poses for the photographer 2000 in Walled Lake, Michigan. The “Monocycle” is equipped with a 40-horsepower engine, 4ft tire and is expected to reach speeds upwards of 100 mph. (Photo by Bill Pugliano/Liaison)

“The September 11 attacks (called September 11, September 11th or 9/11), were a series of four coordinated suicide attacks against targets in New York City and the Washington, D.C. area on September 11, 2001. On that morning, 19 terrorists from the Islamist militant group al-Qaeda hijacked four passenger jets. The hijackers intentionally crashed two planes into the Twin Towers of the World Trade Center in New York City; both towers collapsed within two hours. Hijackers crashed a third plane into the Pentagon in Arlington, Virginia. When passengers attempted to take control of the fourth plane, United Airlines Flight 93, it crashed into a field near Shanksville, Pennsylvania, preventing it from reaching its intended target in Washington, D.C. Nearly 3,000 died in the attacks”. – Wikipedia

Photo: A firefighter breaks down after the World Trade Center buildings collapsed September 11, 2001 after two hijacked airplanes slammed into the twin towers in a terrorist attack. (Photo by Mario Tama/Getty Images)

An injured young woman is led away after an incident at Parsons Green underground tube station in west London on September 15, 2017. Police and ambulance services said they were responding to an “incident” at Parsons Green underground station in west London on Friday, following media reports of an explosion. A Metro. co. uk reporter at the scene was quoted by the paper as saying that a white container exploded on the train and passengers had suffered facial burns. (Photo by Luke MacGregor/Reuters)

A Pegasus airplane is seen stuck in mud as it skidded off the runway after landing in Trabzon Airport, Turkey early Sunday on January 14, 2018. A passage plane which belongs to Turkey's Pegasus Airlines skidded off the runway of Trabzon airport Saturday and ended up halfway down a steep slope into the Black Sea, Turkish media reported on Sunday. 162 passengers and crew on board were safely evacuated. (Photo by Hakan Burak Altunoz/Anadolu Agency/Getty Images)

A security officer looks at a scanning screen for checking passengers' temperature at the Istanbul Airport in Istanbul, Turkey, on June 9, 2020. Technology and innovation will top the precautions of Turkey's biggest airport Istanbul Airport against the COVID-19 in the post-pandemic era, according to the management of the airport. The management on June 9 presented their final preparations and measures taken against coronavirus while Turkish airline companies are preparing to resume their international operations the next day. (Photo by Yasin Akgul/Xinhua News Agency via Getty Images)

A simulated casualty is evacuated during an emergency services exercise at the disused Aldwych underground station on February 22, 2012 in London, England. Operation Forward Defensive aims to test the response to a terrorist incident on the London Underground network during the 2012 Olympic Games. (Photo by Peter Macdiarmid/Getty Images)

Trainees of the Tianjiao Special Guard/Security Consultant bodyguard training camp watch their instructor use a scarf to cover a student's head during a demonstration of close-quarter combat skills at a special course on flight safety inside a scale model of a passenger jet at a flight attendant training centre on the outskirts of Beijing, March 18, 2014. Inspired by the missing Malaysia Airlines Flight MH370, the company wanted to emphasize the importance of aviation safety by teaching their trainees emergency evacuation procedures and close-quarter combat skills to handle situations such as natural disasters and plane hijacks, according to the company. (Photo by Jason Lee/Reuters)

A relative, right, breaks down as rescuers carry the body of a victim after 14 coaches of an overnight passenger train rolled off the track near Pukhrayan village Kanpur Dehat district, Uttar Pradesh state, India, Sunday, November 20, 2016. Dozens were killed and dozens more were injured in the accident. (Photo by Rajesh Kumar Singh/AP Photo)