Imagine the Columbia River Gorge with a roof on it.
It wasn't the Planet of the Apes in my dream last night; it was more like the Planet of the Animals, and I and several other people were stuck on it. We were hiding out in an enormous terrarium -- basically the Columbia River Gorge with a roof on it -- wondering if we were going to be chased by the residents man-animals. No; they were studying us, and (on the few occasions late in the dream when I saw the man-animals face to face) talking to us. And they were surprised at our smarts, and our odd off-world ways, or something.
The planet still had soft drinks, so it was clearly civilized. (Maybe we brought them. Ah, a dream with an unanswered question!)