The Faerieland, sometimes referred to as the Faerie and the land under the hill, is the underground abode, palace or city dwelling of the faeries. Not much is known about the division of the territories between the Courts.
The Faerie is massive, described as a realm and one can travel in it like in a country, and its corridors almost maze-like if traversed without a guide. It does not have a consistent layout and, thus, seems to change often. Though it does not tolerate being surveyed, thus no map of the land has ever been produced.
Time flows at a different rate in the realm, sometimes slower, sometimes faster. Seasons can change in the blink of an eye, mountains and caverns can appear where minutes before no such things were visible, and its rivers change their courses at the whim of some unknown force.
Food or drinks from the court are known to have hallucinogenic and euphoric properties, particularly faerie narcotics and alcoholic beverages. When ingested, these may trap people, mundanes and Shadowhunters, in the Faerie until dismissed by the Queen of the Court. It is possible to convince or bargain with a faerie, to guarantee the protection and one's freedom; however, these deals are often subject to the usual faerie trickery and duplicity.
There are several entrances to the land, most of which tend to be hidden and unguarded and are normally found in natural surroundings rather than in man-made areas; they are often given away by some aspect of their natural appearance that is "wrong" or "off"—like a reflection in water that does not match the world above the reflection. One known entrance is through Central Park, accessed by stepping backwards into the reflection of the moon on Turtle Pond; this path leads to the Seelie Court.
Although commonly located in a single, permanent place, these entrances may be closed or moved when it becomes dangerous or unworkable. In the rare case when wars break out between fey courts, entrances are closed or guarded.
While there are presumably more passageways leading to different places, there are two known tunnels: one leads to the mundane world, and another goes to Hell, particularly Edom, though this one was supposedly destroyed by Sebastian Morgenstern. After the Cold Peace was established, the entrances to the Faerie were sealed off.
Late in 2007, the Seelie Queen requested an audience with the young Shadowhunters of the New York Institute. She had a knight, Meliorn, pass on a message to Isabelle Lightwood and her friends. They went to the Faerie, using the entrance at Central Park. They arrived at a tunnel filled with vines and were met by Meliorn, who escorted them to the throne room of the Queen, who wanted to discuss the recent death of one of her subjects. In particular, he wanted to meet with Clary and Jace.
Even before they arrived, the Queen already had a plan for them. During the meeting, a pixie offered Clary a drink with rose petals floating on top. Clary squeezed the petal and got some juice on her fingers, so when, after a sprite pricked her finger and drew blood, Clary sucked on it, she also unintentionally drank some of the juice, forcing Clary to stay in the Faerie unless she follows the advice of the Queen —to have the kiss she desires the most, which just happens to be with her 'brother', Jace. Though the Queen had already known that they were not actually siblings, she let them go on, playing on their conflicted feelings. When they finally kissed, she let them go.
At one point, Clary rung the bell that the Queen gave to her, if ever she finally decided that she needed help, in exchange for a favor to the Queen. With a group, they were brought back to the Faerie after the bell was rung. They asked for aid in the search for Jace, and the Queen promised to help them if Clary stole the faerie rings from the New York Institute's gallery.
Road to Hell
In the Seelie Court, Sebastian Morgenstern became a frequent guest, particularly in the Queen's bedchamber.
While the Queen was speaking to Gwyn ap Nudd in the throne room, Clary, Jace, Alec, Isabelle, and Simon Portaled into the corridor just outside of the throne room; because of their undetected presence, the group overheard and learned of the Fair Folk's betrayal of the Nephilim. It was only after Meliorn came and told the Queen that the group revealed themselves. The confrontation led to Meliorn's death, and when other faeries came to help, Clary drew a rune on her doorway that blocked their way.
Making a deal with the Queen, she agreed to lead them to Hell, believing that they will not survive. The Queen swore, carefully worded, to not tell Jonathan that they "came" to the Faerie, and later told him that they had left for Hell.
Believing that Clary had agreed to be her queen, Jonathan sealed the borders and permanently closed the gates between Edom and the Faerie.