When Madonna first skipped onto the pop landscape with her ragged lace and taboo-baiting themes in the ‘80s, it was but the opening charge from a born monarch. She's experimented with bubblegum and flirted with gospel sounds. She's nodded to ‘60s girl groups. She's incorporated trance, trip-hop and dubstep into her dance-floor anthems. And all the while Madonna has scarcely broken a sweat across her unapologetic and imperious brow. From the call to arms of “Express Yourself” to the ABBA-sampling kiss-off “Hung Up”, the Queen of Pop's crown jewels are a dazzling array of pop brilliance.