The "Book of Souls" is the title of the sixteenth studio album by the British heavy metal band Iron Maiden, released on September 4, 2015. The album features a blend of heavy metal and progressive rock elements, showcasing the band's signature sound. It includes tracks inspired by various themes, including history, literature, and mythology. The album consists of eleven songs, with notable tracks like "Speed of Light" and "Empire of the Clouds." It received positive reviews from critics and fans alike, praised for its musicianship and lyrical depth. The "Book of Souls" also marked the first double album in Iron Maiden's discography.