View looking south at the double pool that was built in conjunction with the Hasmonean Palace during the reign of Alexander Jannaeus (103–76 BCE). It was refurbished by Herod the Great.
Each pool measures 42 x 60 ft. and each is 10 ft. deep. Note the staircases that lead down into the north (near) and south (far) basins. A wide wall separates the two basins.
It was probably here, in 35 BC, that the brother-in-law of Herod, the young High Priest Aristobulus III, "accidently" drowned while "playing" with some of Herod's youth. His death marked the end of potential Hasmonean take over of Herod's throne.
(53) Upon all this Herod resolved to complete what he had intended against the young man [Aristobulus III]. When therefore the festival was over, and he was feasting at Jericho with Alexandra, who entertained him there, he was then very pleasant with the young man, and drew him into a lonely place, and at the same time played with him in a juvenile and ludicrous manner. (54) Now the nature of that place was hotter than ordinary; so they went out in a body, and of a sudden, and in a vein of madness; and as they stood by the fish ponds, of which there were large ones about the house, they went to cool themselves [by bathing], because it was in the midst of a hot day. (55) At first they were only spectators of Herod’s servants and acquaintances as they were swimming; but after a while, the young man, at the instigation of Herod, went into the water among them, while such of Herod’s acquaintances as he had appointed to do it, dipped him as he was swimming, and plunged him under water, in the dark of the evening, as if it had been done in sport only; nor did they desist till he was entirely suffocated. (56) And thus was Aristobulus murdered, having lived no more in all than eighteen years, and kept the high priesthood one year only; which high priesthood Ananelus now recovered again. (Josephus, Antiquities of the Jews 15:53–56).
See Netzer, Ehud, and Rachel Laureys–Chachy. The Architecture of Herod, the Great Builder. Grand Rapids: Baker Academic, 2008, pp. 42–80.