In some of my games I encounter this kind of spot when settling a new city: a hill, a river and a mountain are located in a way that you can only use two of them for their full benefit. This means: 1. You can settle on the hill adjacent to the river, but the mountain will be 1 tile away, thus denying the Observatory. 2. You can settle on the hill adjacent to the mountain, but the river will not be next to the city, thus denying all river-based buildings. 3. You can settle next to both river and mountain, but on a flat tile with lower production. Assuming this is the 3rd-4th city and your choice won't affect your reach to crucial resources, where would you pop the Settler?