The oldest physical evidence, from blocks found on-site, of the worship of Isis dates back to the reign of the 25th-Dynasty Ethiopian pharaoh Taharqa (690–664 BC). During the 30th Dynasty, Nectanebo I built the temple's more imposing structures. The major part of the temple complex is the legacy of the pharaohs who ruled over Egypt between the reigns of Ptolemy II Philadelphus (285–246 BC) and the Roman emperor Diocletian (284–305 AD). The cult of Isis was upheld until the first half of the 6th century AD, when Justinian abolished the ancient Egyptian beliefs of the temple, by force.
The consequences of building the first dam on the Nile south of Aswan were alarming. In the case of Philae Island, water partially submerged the Temple of Isis when floods filled the dam as a result of seasonal rains upriver. Archaeologists feared that this periodic flooding would soften the monument's foundations, causing it to collapse. It was not until 1960, with the construction of the second
dam, that UNESCO and the Egyptian Antiquities Service decided to preserve Philae and other important Upper Egyptian temples. The dismantling of the Philae complex started in the early 1970s, when a huge cofferdam was erected around the island. Then nearby Agilqiyya Island was carved so that the Temple of Isis would stand just as it had on Philae, and the whole complex was moved and meticulously reinstalled on Agilqiyya. The process took until 1980, when authorities reopened the site to the public.
The first sight that strikes you, once on the island, is the long first court, surrounded by a series of refined columns, all unique. The first building on the left is the Kiosk of Nectanebo I. The westcolonnade, built during the Roman period, leads up the west side of the island. In the first court, turn east to admire, from right to left, the Temple of Arensnuphis, the Chapel of Mandulis (both are Nubian gods), the first east colonnade (Roman period), and Ptolemy V Epiphanes's small Temple of Imhotep.
The first court leads to the first pylon of Ptolemy XIII Neos Dionysos. Both of the obelisks erected in front of the pylon are now at Kingston Lacy, in Dorset, England, taken there by Giovanni Battista Belzoni in 1819. Belzoni (1778–1823) was an Italian explorer, adventurer, and excavator. His methods destroyed a lot of valuable material, but considering the techniques used in his day, he was no worse than other archaeologists.
The small mammisi (chapel) on the left side of the second court was erected in honor of the birth of Horus. Earlier New Kingdom (1539–1075 BC) counterparts of Greco-Roman mammisi are reliefs depicting the divine birth of the king, as in Hatshepsut's temple at Deir al-Bahri (Luxor West Bank) and Thutmose III's shrine in the Temple of Luxor (East Bank).
At the north end of the second court, through the second pylon, the hypostyle hall is the actual entrance to the Temple of Isis. It consists of 10 columns and is mainly the work of Ptolemy VIII (Euergetes II). The majority of the reliefs on the walls are offering scenes: the king, by himself or accompanied by his wife, donates incense, vases, and wine to the gods to please them.
It is not uncommon to hear scholars call the art of the Greco-Roman period decadent and coarse. Although it is less classically Egyptian than the art of preceding periods, it nevertheless is an interesting mixture of Hellenistic and Egyptian traditions. At the same time, the religious beliefs—the most important part of the functioning of the temples—remained the same throughout the centuries, because the temples gained a degree of independence inside Egypt.
As with every temple, the sanctuary is the focal point in the complex. The pronaos, behind the hypostyle hall, was converted into a Coptic church, with an altar visible on the right—which also explains the crosses on the walls. To the east of the Temple of Isis, close to the riverbank, the unfinished Kiosk of Trajan is a small open temple with supporting columns. Inside are offering scenes.
The Sound & Light Show, like the one at the Temple of Karnak, has two parts. The first is a walk through the partly illuminated temple, and the second delivers a brief history of the site combined with music and the light show. It is a pleasant spectacle, less showy than that at Karnak.