Basement Key
Antechamber
Foundation
The Grounds, fountain
Estate:Unknown
Car Keys
File Cabinet Key
Archives
Foreman's Office
The Grounds, tunnel
Laundry Room
Patio
Key 8
@Keycard
Special uses:
- Foundation - elevator call button
- Unknown (permanently stays open)
Key of Aries
Underground:Unknown
Treasure Trove
Key to the Secret Garden
Master Key
Prism Key
Freezer always has one, if you have a Lighter
Planetarium always has one, after some Telescope uses
Sanctuary Key
see list
Silver Key
Mechanarium always has one
Good chance of finding an Antechamber lever: