We first see pylon shaped structures in the mortuary temples of the Old Kingdom pyramid builders, from which the later, more massive structures may have evolved. Not only were they one of the most distinctive architectural element within the temple complex, but were also very popular with the pharaohs. Thus, while they acted as the entrance gateway to the temple proper, they were very often enclosed within the temple itself, as successive rulers extended temple complexes.
As the rulers added pylons to the temple complexes, particularly later in Egypt’s history, they often tore down existing structures that they felt were no longer useful and stood in their way, and used this rubble to fill the interior of their new pylons. Interestingly, the material from these prior buildings was thus preserved, encased in the mortar of the standing pylon. Some, such as the White Chapel of Senusret I and the Red Chapel of Hatshepsut (in the Open Air Museum at Karnak) have been salvaged when pylons have been restored, and pieced together to form as nearly as possible the original structure. Their decorations often represent some of the finest and best preserved examples we have from Egypt’s ancient monuments.
In some cases, blocks from such structures were also reused in the outer walls of the pylons, as in the case of the first pylon at the Temple of Amun at Karnak. Later pylons, such as the one built during the Greek period at the Small Temple of Medinet Habu, were constructed simply of some combination of brick and stone.
Like the enclosure walls, pylons served both a defensive and religiously symbolic function. They provided a physically defensive position in times of real chaos or attack, but they also, like the enclosure wall, provided a symbolic barrier to the chaos and evil beyond the temple grounds. In fact, the Egyptian name for pylons during the 18th Dynasty, Bekhnet, seems to derive from a term meaning “to be vigilant”.
Furthermore, the most common form of decorative theme related to pylons from the New Kingdom onwards is the smiting of enemies by the King. From the earliest dynastic periods, we find scenes depicting the Egyptian king, towering over his opponents, in the act of smiting them with a club or short sword called a khepseh. This motif may have also adorned earlier pylons, though most of these are lost to us.
However, symbolically the pylon had one other important role, mimicking the shape of the akhet, or horizon hieroglyph. It was here that the sun rose over the earth’s horizon between the outer world and the hidden, sacred grounds of the temple.
Colorful flags decorated with fetishes were mounted on poles which were than set into the face of the pylons. These flags had their origin in the very earliest of Egyptian temples, and their shape was almost surely responsible for the flagpole hieroglyph for god (ntr and variations such as nutar). Though not a single example of such a flag has been discovered, documentary evidence suggests that they may have been monumentally large, reaching heights of some 60 meters (200 feet) and weighing more than five tons. It seem, like all things monumental in Egypt, the raising of these flags into the pylon niches would have been a difficult task, but it has been suggested that this was accomplished by a rope/pull system that may have been used to raise sales on the Egyptian boats.
Regardless, the pylon represents the end of the beginning, for through this monumental gateway stood the courts of the temple proper.