Palace of Darkness

The Palace of Darkness is the first dungeon of the Dark World in A Link to the Past.

It is located in the east, in the area were first stood the Eastern Palace. The main treasure is the Magic Hammer. The end boss is the Helmasaur King. After defeating him you receive a Heart Container and the 1st Crystal.

Access to the dungeon is granted by walking through the maze. Eventually, a monkey named Kiki will follow you and ask for ten rupees. Give him the requested amount and continue towards the dungeon. There, the monkey will offer to reveal the dungeon's entrance for one hundred more rupees. Give him these as well and he will open the dungeon for you by hopping onto an otherwise unaccessable switch.

In Four Swords Adventures, it is where Link finds the Red Maiden.

When you enter the dungeon in the GBA remake of A Link to the Past, the dungeon's name is just "Dark Palace".