Mimban was a shrine to the deity Pomojema. A large ziggurat made of volcanic rock, it contained an enormous statue of Pomojema, imbedded in which was the Kaiburr crystal. The temple also had a deep sacrificial well within it.
In 2 ABY, Luke Skywalker and Leia Organa came to the temple to retrieve the Kaiburr crystal. They were there attacked by Darth Vader, but managed to escape after Vader fell into the temple's well.