Summit Museum, at the top of Mount Diablo in Mount Diablo State Park, is in a historic 1930s stone building that is also the park's visitor center. Exhibits depict the park's natural and cultural history, and a rock wall and accompanying video recount geological forces that formed the mountain. A diorama with audio features presents an overview of park ecosystems. Key features are shown on a model of the mountain. There also are high-quality displays of artwork and photos.
A circular stairway leads to an observation tower with a deck that provides panoramic 360-degree views; marine fossils embedded in the building's sandstone walls can be seen on the way up.