Hitman: Absolution

Spoiler ** Found a nice way of getting around the level unhindered. If you are on normal mode and want get some challenges done the easiest way is to get one of the 3 guards that follow Layla about and take their disguise. When you start on top of the lift immediately go to the ledge and walk along it, drop down and go around to the door and through it. If you are quick enough you should see the last of Layla's guards walking into a hallway on the left. Garrote him and dump him in the chest that is right there. Nobody should see this and you can then stroll about and take the other two out when you get into the room by the panic room. You are then free to go where you wish. Except dexters room and armoury. Those are still trespass violations I believe. Hope this helps

(Warning this guide/video contains spoilers!...)

The video below is mine, and this is the steps to get this achievement.
Difficulty doesn't matter, and it always works the exact same way.
What i describe here is exactly what i do in the video:

Run by the door in the beginning, you'll get the attention of one of her elite guards. Subdue/kill the guard,get the disguise and dump him. Then find the keycard, and follow her to the panic room...
IF you actually missed the timing i did, just head right inside the room and wait for her, might take a few min but she'll eventually go there.

Then you actually get to destroy something beautiful... (The Achievement doesnt pop for me because i already had it.)