making it the most expensive work of music ever sold.

The album was recorded in secret over six years from 2007 to 2013. A single two-CD copy was pressed in 2014 and stored in a secured vault in Casablanca, Morocco, then sold through the auction house Paddle8 in 2015. A legal agreement with the purchaser stipulated that the album cannot be commercially exploited until 2103, although it can be played at listening