Looking to unlock every hidden door in The Blue Prince? You’ll need to collect all the Sanctum Keys scattered throughout the game. In this guide, we’ll show you where to find every Sanctum Key, what you need to do to get them, and how they help you progress through the game.
Sanctum Key #1
You can find the first Sanctum Key in The Blue Prince on the desk in Room 46. To get it, you’ll need to finish the game and then return to Room 46 a second time. When you go back after completing the game, the key will be waiting for you on the desk.
Also Read: How To Reach Room 46
Sanctum Key #2
The second Sanctum key can be found in the Clock Tower. Solve the Clock Tower Puzzle in Blue Prince to receive the second Sanctum Key.
Sanctum Key #3
The third Sanctum Key is located in the Throne Room. To get it, first collect all the Microchips and place them on the pedestal in Blackbridge Grotto. Doing this will unlock a hidden path that leads to an altar, where you’ll find the Throne Room floor plan. Then draft the Throne Room and go inside to collect the key.
Also Read: Blue Prince: All Microchip Locations (How To Unlock Throne Room Floorplan)
Sanctum Key #4
Sanctum Key #4 can be found at the bottom of the drained Reservoir. To access it, you’ll first need to draft the Pool Room, then connect a Boiler Room to a Pump Room in your blueprint. This setup will allow you to drain the water from the Reservoir.
Once it’s empty, head to the Foundation and use the lift to reach the now-accessible lower area. Down there, you’ll find several locked chests — and one of them holds Sanctum Key #4.
Sanctum Key #5
This Sanctum Key is located in the Vault. To get it, start by finding the Lost and Found floor plan in the Basement. Once you have it, draft the Lost and Found room to receive the Deposit Box Key #370. Next, draft a Vault room, go inside, and use Key #370 to unlock Vault #370. Inside, you’ll find the Sanctum Key waiting for you.
Sanctum Key #6
To get Sanctum Key #6, you need to carefully control the water levels in the Reservoir. First, make sure you connect a Boiler Room to a Pump Room in your blueprint. Then, fill the Reservoir until there is only one empty segment left. This specific water level lets you use the Tomb (as your Outer Room) to access the boat and move it to the other side of the Reservoir.
Once the boat is on the other side, go back and drain the Reservoir until six segments are filled. With the boat now on the correct side and the water at the right level, head to the Foundation, take the lift, and hop onto the boat.
The boat will take you to a hidden area called the Safehouse. Inside, look around to find the Sanctum Key #6 sitting on a crate next to the sofas.
Sanctum Key #7
Sanctum Key #7 will appear in the Music Room, but only if you’ve drafted enough rooms in the house during that run before adding the Music Room. Make sure to draft more than 30 rooms before finally drafting the Music Room. This will trigger Sanctum Key #7 to appear inside the Music Room when you enter it.
Sanctum Key #8
Sanctum Key #8 can be obtained by first finding the Mechanarium floor plan in the Reservoir area. Once you have it, draft the Mechanarium after drafting the 6 other “Cog” rooms in the same run. This will make the Mechanarium have 7 doors, and the key will be located behind the last door.
