Abandoned for thousands of years, it had long been occupied by a living, mindless, consuming, evil, fog-like entity called Mashadar. The city has recently been destroyed.
Ancient history During the time of the Trolloc Wars, Aridhol was one of the Ten Nations, ruled by King Balwen Mayel. A man called Mordeth, the king's advisor, corrupted the king and the city, bearing resemblance to Grigori Rasputin. The city that adopted the motto: "The victory of the Light is all," became darker, and gave birth to Mashadar, which consumed and corrupted it. A large army of Trollocs and Myrddraal camped there later in the war; not one Shadowspawn came out alive. Since then, Shadowspawn have avoided the city.
Recent events In The Eye of the World, Moiraine Damodred led the group of people fleeing from the Two Rivers to camp there. While there, Rand al'Thor, Perrin Aybara, and Mat Cauthon met Mordeth, and Mat picked up a cursed ruby dagger. Ba'alzamon drove Shadowspawn into the city. Padan Fain went into the city and melded with Mordeth.
In Lord of Chaos, Rand Traveled to Shadar Logoth accompanied by Aiel and Ogier to close the Waygate in the city. While there, one of the Maidens of the Spear, Liah, disappeared.
In A Crown of Swords, Rand hunted down the Forsaken Sammael in Shadar Logoth. Sammael was killed by Mashadar. Rand also saw Liah again; when she was caught by Mashadar, Rand killed her with balefire so that she would not suffer.
In Winter's Heart, Rand and Nynaeve al'Meara used the One Power to set the evil of Shadar Logoth against the evil of the Dark One's taint on saidin. The two evils annihilated each other, cleansing the taint on saidin in the process, and Shadar Logoth was completely destroyed, leaving a massive hemispherical crater. This leaves Padan Fain, and his dagger, as the only remnant of the evil of Shadar Logoth.