A New Zealand teenager built the world’s longest piano in his backyard.

Adrian Mann began his ambitious project in 2005 at the age of 15 in Timaru, New Zealand. He named the instrument the 'Alexander Piano' in honor of his great-great-grandfather. The final structure measures 5.7 meters in length and weighs approximately 1.2 tonnes. This is significantly larger than a standard concert grand piano, which typically measures around 2.7 meters.The physics of the piano rely on string length and tension to produce sound. In a standard piano, the bass strings are often wrapped in copper to add mass because the cabinet is too short for the ideal string length. Mann’s design uses much longer, thinner strings that do not require as much winding. This results in a purer harmonic series and a more natural bass resonance.The longest string in the Alexander Piano is about 4.8 meters long, nearly double the length of those in a Steinway Model D. Mann spent roughly 5,000 hours over four years perfecting the action and soundboard. In 2009, the piano was moved from his farm shed to a professional studio. Today, it is recognized globally for its unique acoustic properties and has been recorded by numerous professional pianists.