After you find The Legend of Zelda: Breath of the Wild’s 12 Captured Memories locations on your Shiekah slate, return to Impa in Kakariko village. She’ll tell you about the last Captured Memory and show you a picture on her wall that can guide you there. If it looks familiar, that’s because you probably visited the field of broken machines early in the game, as you first made your way to Hateno village.
Warp to Hateno tower. Your destination is over the Squabble river, in the field full of broken-down machines in front of Fort Hateno. See the map in the gallery above for the exact location, which is in the greater Blatchery Plain area.
You won’t find any great reward waiting for you, but be patient. Finding this 13th Captured Memory adds a scene to Breath of the Wild’s ending.