During Chapter III, you'll speak to Fleur and gain the ability to see blue images on the wall, which is necessary to get in the wine cellar. Before going there, go outside and go to the observatory on the right hand side, go into ghost form and interact with the symbol on the wall on the bottom floor.
It can be seen in this 100% walkthrough at
41:44.
Using the above video will get you ALL the achievements in the game in about an hour.