Eureka (location)

Eureka, the Forbidden Land, is an optional dungeon in the game Final Fantasy III which contains some of the best equipment in the game. A gateway to it can be found at the bottom floor of the Crystal Tower, but the Eureka Key is required. Doga and Unei unlock the Eureka Key, and give it to the Warriors of Light, granting them access to Eureka, knowing they need better equipment to fight Xande.

Shops
In the final area of Eureka you can find three shopkeepers selling some of the best spells, summons, and equipment in the game. It is also worth noting that this is the only place where Shuriken can be purchased, though at an ridiculously high price.

Hidden Shop
To discover the hidden shop the player must walk to the right, through the wall on the screen where the other two shopkeepers stand.

Monsters

 * Abaia
 * Sleipnir
 * Haokah
 * Acheron
 * Oceanus
 * Ninja (Boss)
 * Amon (Boss)
 * Kunoichi (Boss)
 * General (Boss)
 * Scylla (Boss)
 * Guardian (Boss)

Music
Eureka has its own exclusive background theme, originally translated "Forbidden Land" in the Original Sound Version, but was retconned as "Forbidden Land Eureka" (禁断の地エウレカ Kindan no Chi Eureka, "Forbidden Land Eureka") in the Original Soundtrack.

Final Fantasy Tactics
The Forbidden Land Eureka was mentioned as one of the wonders in Final Fantasy Tactics. It bears the following description:
 * This once prosperous capital of the Kashka Dynasty was destroyed in the Cataclysm, along with the vast legacy of its royal family. It is now a necrohol, populated by spirits drawn to the shades of its past glory. 

Etymology
Eureka (Gr. εύρηκα) is a historically famous Greek word that means "I have found it".