They next entered the fields where roam the heroes who have fallen in battle. Here they saw many shades of Grecian and Trojan warriors. The Trojans thronged around him and could not be satisfied with the sight. They asked the cause of his coming and plied him with innumerable questions. But the Greeks, at the sight of his armor glittering through the murky atmosphere, recognized the hero, and, filled with terror, turned their backs and fled, as they used to do on the plains of Troy. Æneas would have lingered long with his Trojan friends, but the Sibyl hurried him away. They next came to a place where the road divided, the one way leading to Elysium, the other to the regions of the condemned. Æneas beheld on one side the walls of a mighty city, around which Phlegethon rolled its fiery waters. Before him was the gate of adamant that neither gods nor men can break through. An iron tower stood by the gate, on which Tisiphone, the avenging Fury, kept guard. From the city were heard groans, and the sound of the scourge, the creaking of iron, and the clanking of chains. Æneas, horror-stricken, inquired of his guide what crimes were those whose punishments produced the sounds he heard. The Sibyl answered, "Here is the judgment hall of Rhadamanthus, who brings to light crimes done in life which the perpetrator vainly thought impenetrably hid. Tisiphone applies her whip of scorpions and delivers the offender over to her sister Furies." At this moment with horrid clang the brazen gates unfolded, and within, Æneas saw a Hydra with fifty heads guarding the entrance. The Sibyl told him that the gulf of Tartarus descended deep, so that its recesses were as far beneath their feet as heaven was high above their heads. In the bottom of this pit the Titan race, who warred against the gods, lie prostrate; Salmoneus also, who presumed to vie with Jupiter, and built a bridge of brass over which he drove his chariot that the sound might resemble thunder, launching flaming brands at his people in imitation of lightning, till Jupiter struck him with a real thunderbolt and taught him the difference between mortal weapons and divine. Here also is Tityus, the giant, whose form is so immense that, as he lies, he stretches over nine acres, while a vulture preys upon his liver, which as fast as it is devoured grows again, so that his punishment will have no end.