Although the album was inspired by the 1927 film Metropolis, it is not intended to be a concept album, unlike two of the band's previous studio albums, Dante XXI (based on Dante Alighieri's The Divine Comedy) and A-Lex (based on the 1962 book A Clockwork Orange by Anthony Burgess).
American Heart Association | Purple Heart | Heart | Sacred Heart | Heart of Darkness | Heart (band) | head | head of state | Beavis and Butt-head | Show of Hands | Heart of Midlothian F.C. | Alec Head | Murray Head | Head Start | Anthony Head | Head Start Program | Diamond Head | Set the Controls for the Heart of the Sun | Human head | heart failure | Head teacher | Clap Your Hands Say Yeah | British Heart Foundation | Machine Head (band) | Machine Head | Head Over Heels | Head of the River Race | Eddie the Head | The Heart of Midlothian | Hilton Head Island, South Carolina |