Part of the quest Starry Night, when Ambrose remembered something from his dream, a painting at the west gate. He asked you to find a painting from the Prontera West Gate.
This quest is quite tricky as there will be no guide shown in the map that help you locate the painting, you really need to find it all over place of Prontera West Gate.
If you read the whole conversation of Ambrose, you’ll find a clue in there telling “In my memory, it seems to be placed near the wall and garden at the west gate!“. It means, the painting is just near the garden where Tammi is. There will be also problem locating this thing, as the camera angle is so close to the wall blocking the view of the painting.
That’s the short guide for the part of Starry Night quest.