Door: Ride the drone back down, get off and wait for it to head up again, and head into its hole to find the door.

Find the one with the blue lights and the lever is at the top of its journey.

Lever: After one of the arena fights in the tower you'll ride some cargo drones up to the next area.

Door: The door is on the right side of the room with the pentagram on the floor shortly after pulling the lever.

Lever: Head up the slope from the rune trial, and the lever is behind some barrels at the near end of the platform to your left.

Door: From the lever, carry on across the bridge and the door will have opened behind the small lava flow.

On the left is a square platform, and the lever is on the edge closest to the lava flowing down.

Lever: From your starting position, jump the gap to your left, cross the bridge, turn right, and head halfway along the next bridge.

Door: The secret area is directly below you, so drop back down the way you came and head under the screen to find it.

Stand on the left handrail and jump up to a small ledge, then climb up to find the lever.

Clear the area of enemies and then climb onto the crates, up onto the narrow walkway above (where the armour pickup is) and make your way along it until you're near the large screen.

Lever: After restoring power and dropping to the lower level, follow the walkway round until you find two large crates.

Door: From the lever, head right to find the door.

Drop down below it, enter the gap in the fenced-off area surrounding it and pull the lever.

Lever: After opening the blue gate and down the path to the left, keep to the left and down below you you'll see the top of a yellow cylindrical structure with a fan inside.

If you're interested in other hidden things, our Doom secrets and collectibles guide can help. We've got the locations of both the levers and doors below.

A chime will sound and a door, hidden elsewhere in the level, will open, leading to retro game heaven. To unlock a classic level, you need to first find a hidden lever and pull it. They're a lot of nostalgic fun to explore, and there are no less than 13 - one in each level of the new game. Like Wolfenstein before it, Doom 2016 has a particularly lavish kind of Easter egg: classic levels from the original Doom and Doom 2, recreated in the new engine in all their original low-resolution-texture, low-poly glory.

Doom 3 free stuff