The site of Behbeit El-Hagara , the old city of Iséum, between Mansourah and Samannoud, is certainly the most spectacular field of the granite of all the Delta of the Nile with its temple of Isis.

The large temple was dedicated to the goddess Isis from where the name of Iseum to indicate this site.

This heap of stones out of granite, whose many ones carry low-reliefs, is impressing at first sight. In the North-West a covered marsh of reeds is. It would be the old crowned lake of the temple.

According to the statements of the travellers of the 18th century and the plan of the Description of Egypt realized by the scientists of Bonaparte, a large enclosure delimited the central temple dedicated to the goddess Isis.

About 1875, Iseum was in a state of complete upheaval. The walls were reversed, the piled up blocks the ones on the others on a great height. It was impossible to recognize in this chaos the primitive plan of this temple dedicated to the goddess Isis.

The crowned enclosure was made of a brick wall believed on 460 meters length and 300 meters broad. Of this immense brick enclosure, there remain nothing any more. The temple itself of Isis had 120 meters length, or 180 by including/understanding the pronaos, and 60 meters of width.

According to the many inscriptions, the temple would have been built by the Pharaon Nectanébo {{II}} of into -360, but decoration only would have been hardly outlined. Indeed, the still visible cornices carry the Egyptian triglyphe with the cartouches of the king Ptolémée {{II}}. They presented elements varied according to the place which they were to occupy in the building. One of the decorative planks carries a head of Isis, alternating with the cartouche of Ptolémée.

As on the major part of the walls of the temple appears the name of Ptolémée {{II}} Philadelphe (- 285/-246), it is to be supposed that this sovereign thus completed the temple of Isis and embellishes it. Ptolémée would have thus added a court preceded by a gantry.

The archeologist Christine Favard-Meeks proposed a historical reconstitution of this temple. The sanctuary of Isis was in the center. In the east of this sanctuary and on the roof, various vaults intended for the worship of Osiris were arranged. A staircase opening on the frontage on the right temple gave access these air vaults which following the example other well preserved examples, as with the temple of Hathor to Denderah, were to fulfill a particular role in the rites and mysteries which were played it. Parts of this staircase of access are still in the middle of the ruins. The temple of Isis was to be preceded by a court surrounded by colonnades. Its access was done by a gantry going back to Ptolémée {{III}}.

Iseum de Behbeit El-Hagara represented one of the major sanctuaries of the goddess in Egypt and formed with that of Philae one of the very popular centers of pilgrimage at the time gréco-Roman.