The existence of ancient ruins in the locality of Mikro Elos (Small Marsh) of Brexiza has been noted by early travelers, who also refer to the area as Nissi (island). In 1792 the French Consul in Athens, L.S. Fauvel, drew the ruins of the area, on an islet cut off from the land by a canal. The excavations have revealed the extensive complex of the Egyptian gods sanctuary and the luxurious bathhouse (balneum), as well as a large ellipsoidal cistern further to the south. Visitors can circulate in the archaeological site after works executed by the Hellenic Ministry of Culture with the financial support of the European Union (3rd Community Support Framework).

The complex was founded by Herodes Atticus, around 160 AD. The great orator, sophist and benefactor hailed from Marathon and resided here, and the complex was possibly established within his estate. The sanctuary can be identified as “the sanctuary of Canopus” referred to by Herodes’ biographer Philostratos (2nd-3rd cent. AD). In founding it, Herodes imitated the Emperor Hadrian, who had built a Serapeion on an artificial islet at Tivoli, close to Rome, modeled on the Serapeion of the town of Canopus on the Nile Delta.