Palace of Darkness

The Palace of Darkness, also known as the Dark Palace, is the first dungeon of the Dark World in A Link to the Past, also known as Level 1, and is the sixth dungeon overall.

Entrance to the Palace
It is located in the east, in the area were first stood the Eastern Palace. Access to the dungeon is granted by walking through the maze. Eventually, a monkey named Kiki follows Link and asks for ten rupees. Link gives him the requested amount and continues towards the dungeon. There, the monkey will offer to reveal the dungeon's entrance for one hundred more Rupees. Link gives him these as well and the monkey opens the dungeon for Link by hopping onto an otherwise inaccessible switch.

Themes and Navigation
This dungeon introduces a greater level of danger than those found in the Light World, introducing Blade Traps and Medusa among a new host of enemies such as Helmasaurs, making their first appearance in the series. Link will encounter special ledges that allow him to perform an autojump when he runs off of them. In addition, some statues can be pushed Link if he touches them, which he must do to pass through dangerous areas and solve puzzles. Strange, eerie creatures known as Goriya mimic Link's moves (similar to Mask-Mimics and Arm-Mimics in later games), and should some of these enemies face Link directly they will fire a bolt of fire at him. This dungeon's treasure is the Magic Hammer, which is used to remove Moles and defeat Terrorpins so that Link can reach the Dungeon Master. The boss is the Helmasaur King, a gigantic Helmasaur. After defeating him Link receives a Heart Container and the first Crystal.

A Link to the Past comic
The Palace of Darkness is also featured in the A Link to the Past comic. After being told by Zora that a Maiden is imprisoned in the nearby palace, Link decides to go and rescue the maiden. Before leaving, Zora allows Link to take Epheremelda as a guide and grants him the Zora's Mask to disguise himself and not look so conspicuous as he is sneaking around the palace.

The duo arrive to the Palace of Darkness and eventually reach the storeroom with the firecorn explosives, and although Link had been able to sneak around with the Zora's Mask without being noticed, he is discovered by a Rocklops. The Rocklops warns Link of what could happen if he set off the firecorns in the palace, but the young hero disregards his warning and takes a Hinox's bomb belt that was wrapped around it. Link then stumbles into the imprisoned crystal, but is attacked by a Gleeock  that was called upon by the Rocklops. Although he defeats it easily  with the Master Sword, soon more Hinoxs riding Gleeocks begin to head   towards him. Link gives Epheremelda ones of the bombs from the Hinox's belt, which  eventually denotes the firecorn stockpile and destroys the entire   palace. This allows the maiden to be freed from the crystal, who thanks  Link and grants him a relic called the Comm-Fork.

Trivia

 * As with the Light World dungeons, this dungeon is translated as a Palace in the English release of the game, but in Japanese it was known as a Temple. The name change likely stems from Nintendo of America's strict policy on mentioning religion in any form at the time. From Ocarina of Time onwards, is always translated as "Temple".
 * The Palace of Darkness shares it's Japanese name with the Shadow Temple of Ocarina of Time, and the Temple of Darkness in Four Swords Adventures, the latter of which is extremely similar in design and offers many of the same threats and obstacles.