Trapped In Ruins - Act 1 Side Quest
Start Location: Kephisos Valley
Quest Location: Kephisos Valley
Objective: Defeat the Ancient Limos
Trapped In The Ruins is an easy quest which you can pick up from Pausanias in Kephisos Valley. Right next to Pausanias you'll also find Isarchus who will give you the Spartans Lost Side Quest. If you're having a difficult time locating either of these two side quests use my map screenshot below for additional guidance.
For the Trapped In The Ruins Side Quest all you need to do is defeat the Ancient Limos who the soldiers trapped in the ruins. He has a very small leash radius which you can use to your advantage if you're ranged, otherwise the quest shouldn't be too difficult for you to complete.