Thanks, but I should have made a note about this. I'm proofing a historical study on ancient history, which the land that it's talking about was ancient, not today. I don't know if I should change the wording or not. That's not the real sentence, and since this is going into a book later, I don't really want to type the actual sentence.
Oh, I guess that he means that it was there at the time, but should it be "sat"? I know he means it was located there at the time. That is what he's getting at, but without changing it to "located," should it be sat?
"The small town set at the mouth of the river" is a sentence fragment - it has no verb!
"Set at the mouth of the river" describes the small town's location. You still need a verb.
If you simply wanted to say where the small town was located you'd use "The small town sat at the mouth of the river" or "The small town was set at the mouth of the river". If you want to make a furth