Antoinette's enormous mansion, contained her, Jamison, and Mozart. It housed them all for years, until Mozart threw dynamite at it, virtually levelling the entire estate by several feet. The nitro glycerin in the attic, and the dozens of underground tunnels allowed this entire lot to be totally demolished in the explosion. All of the alchemy fled the house, and fizzled away.
This house has (primarily) a kitchen, living room, and torturing room. And although those are the only ones we really see, there are likely tens of other rooms, as the mansion is several thousand square feet.
Nearby the mansion, there is a blissful garden, a river, stream, and massive cliffs with a waterfall going off of them into a bay behind her property. David uprooted her entire garden to replace it with a pond. This would allow him to more easily create a portal. There are several extremely large trees around the property as well, and her driveway is basically an extremely narrow, extremely winding, EXTREMELY high up pathway, with hundreds of feet into an abyss below.