Philae was among the last places in Egypt to succumb to Christianity. During the sixth century, after the Romans succeeded to kneel down the old kingdom, the cult of the deity Isis was banned and the beautiful Egyptian construction was transformed into a Christian church. The ancient symbols were scratched off the walls and replaced with crosses but the temple still remained itself, even under the Christian covers. Not long after, Christianity was cast away from the region by Islam, but the new rulers were not interested in the settlement at Philae or the Temple of Isis, so the place was simply abandoned.
The Temple of Isis is, though, the most important site to visit on Philae. It is made of a small court, where a hypostyle hall stands. From there, you can enter the inner temple, impressive with its twelve chambers. The most interesting part of the temple is the sanctuary, where the walls are decorated with hieroglyphs and illustrations of scenes involving pharaohs.
Once inside the inner court, you will notice how pylons are surrounding the temple on its north and south sides while Mammisi is guarding it from the west. The east is guarded by a portico from where you can gain access into some small chambers. Because the north and south Pylons were not erected parallel one with another, the inner court has quite a strange shape.
Mammisi is the name of the Birth Room. Also known as House of the Divine Birth of Horus, which is the son of Isis, the deity honored by this temple. It was erected during the first century of the first millennium. The walls of this room are carved with scenes showing how Isis gave birth to her son, Horus, the god with the falcon head. The sides are guarded by porticos, while on the east, the pylons are adorned with a representation of the goddess that oversees the inner court.
Another impressive construction in Philae is the Kiosk of Nectanebo I. Among the last constructions erected by a pharaoh, the kiosk is also known for the columns topped by the head of goddess Hathor.
Among the Roman vestiges, you will find the Temple of Augustus, erected at the beginning of the first century. The temple is now in ruins, as its stones were carried from here to serve to building new churches by Christians.
Besides the Temple of Isis, there are many other monuments that you can visit in Philae. One is the Gate of Emperor Diocletian. This looks like a Roman triumph arch and was designed in the Roman architectural style. The structure consists of three different arches, with the biggest in the center and the other two flanking it. Nowadays, only the sides still stand; the gate was used by the Romans to gain access to Philae from the north.