Up until 1987, the largest piano was the 1935 British Challen & Son Concert Grand built for King George V and Queen Mary’s silver jubilee—it is over 11 feet long. (Interesting side note: The Beatles played on a Challen upright at the Abbey Road Studios for the tunes Paperback Writer, Tomorrow Never Knows, Old Brown Shoe and Ob-La-Di, Ob-La-Da.)
The current honor now goes to the “Klavins-Piano Model 370,” also known as ‘The Giant,” built by German-Latvian, David Klavins (b. 1954). And it is over 12 feet (370 cm high) tall, weighing over 2 tons. However, this may soon be challenged by the next generation of Klavins, Model 450i, which is already in production.