Behbeit El Hagar is an archaeological site in Lower Egypt. It contains an ancient Egyptian temple for the goddess Isis. The site lies along the Damietta branch of the Nile, north of Sebennytos and 8 kilometers (5 mi) west of Mansoura. The temple is known as the Iseion, and was the first large temple to have been dedicated to Isis. In earlier shrines at the site, she may have been worshipped alongside her mythological husband, Osiris, and son, Horus. It was begun by the kings of the Thirtieth Dynasty (380–343 BC) and completed under Ptolemy III (r. 246–222 BC).