With a total surface area of almost 7000 m2, the west façade of Cologne Cathedral is the largest ever church façade created. Its form, with its two imposing 157 metre spires crowned with magnificent filigree spires, can be traced back to a medieval architectural drawing known as Facade Section F, a parchment document drawn in the year 1280, almost one hundred years before work actually commenced on the building of this facade In 1360. Work on the spires was not however completed until 1880. Despite a richness verging on excess of detailed shapes and decorative details, the facade is nonetheless based on a very clearly visible and simple structure. To reflect the five parallel aisles running down the main body of the cathedral, the lower two floors of the cathedral facade are constructed down five separate axes. The two lower floors of the spires with their narrower axes occupy the same width as the outermost side aisles while the broader central axis, featuring the centrally located Marienportal doorway and the giant West Window above it effectively echo the centre aisle of the interior which, de facto, extends as far as the centreline axis of this window. At ground floor level, three of these five axes feature portals. The largest of these, the centrally arranged Marienportal is flanked on its northern side by the Dreikönigenportal (Three Kings) and, on its southern side by the Petersportal which is actually the only genuine medieval doorway to the cathedral. The outermost axes are home to double stained glass windows. On the upper storey, the giant central window is framed by four narrower windows, arranged in pairs in each spire. All floors are arranged in a similar pattern: a filigree stained glass window rises above a plinth area and its crowning feature provides a transition to lead the eye up to the next floor, thereby lending emphasis to the verticality of this façade. Above the two-storey lower structure which reaches a height of 45 metres, the two free-standing 112 metre spires soar heavenwards, and a transition from square to octagonal cross section is managed unobtrusively so as to be almost invisible. This transitional feature is veiled by the gigantic structures of the filigree spires which narrow as they rise, almost to a vanishing point above the main buttresses on their four corners from which the octagonal structures gracefully and elusively emerge. As you let your gaze travel up the full height of these two spire structures, you trace a path up the steeply inclined roofing caps which culminate at their dizzying maximum height with majestic 9 metre high flowering cross structures.