Opened in 2006, the museum has been designed to provide world-class facilities for the research, curation, and presentation of the nearly one million specimens discovered during the development of Diamond Valley Lake in Hemet.

Its special environmental features include solar panels on the roof, cold-water pipelines running underneath the floor to reduce air conditioning, landscaping with low-irrigation native foliage, and extensive water reclamation.

In 2008, it was awarded LEED Platinum Status by the US Green Building Council, their highest rating, and was the first museum in the United States to receive the recognition.

Among the artifacts on display are pieces donated by the Domenigoni family, the original settlers of the valley, and the Soboba band of Luiseño Indians that inhabited the area before them.

Also featured in the gallery is "Li'l Stevie", one of the most complete mastodons known from the western United States, who is displayed unreconstructed and still partially buried as found when it was first uncovered.