Rubik’s 5×5 Professor’s CubeThe Most Complex Rubiks Cube One of the largest Rubiks Cubes created, the 55 promises to push your problem solving capacity. Known as the Professors Cube due to the sheer difficulty to complete it! This Rubiks Cube features six different colored sides, each made up of 25 squares. Once the faces are jumbled up, you are going to need to twist, turn and rotate the puzzle until each of the six faces has only one colour. Seems nearly impossible, right?