Trouble for the tower building is not the babylonian confusion of tongues, but the contour of the little wooden blocks. The difficulty: up to four coloured glass marbles per block are glued into some indentations of the 24 beech wood cubes. Other cubes show spherical indentations in the same place. The tower arises level by level on a 4-cube base, where a glass ball must nestle in every recess, however none of the marbles must stick out.