Pyramid

Spoiler Warning: This page contains spoilers which may affect your IVAN experience negatively

"You see here a crumbling pyramid"

The pyramid only appears on your map after you receive the relevant quest from Myrddin Wyllt. It has several levels with many coffins and a maze of twisting little sandstone hallways all alike.
One room will be full of a river of quicksand which is functionally the same as water.

Bunker

The penultimate level housing the thaumic bomb.

The floors and walls are made of supercrete and there is a large room especially for housing the bomb with lead walls and an inner glass chamber. Several mind worm boils are trapped within cages of stainless steel bars as psionic 'guard dogs'. They can be seen but not (easily) hit through their cages and getting to the bomb will put you within range of at least one of them. Without a specific kind of helmet to negate their psi attacks they can kill even a strong player.

Getting into the bomb vault isn't hard as the outer door locks aren't n unusual type nor the walls especially strong. Getting the bomb OUT harder as part as it weighs a whopping 100001g and cannot be changed into a lighter material. A Leg Strength of at least 41 is required to pick it up without being Burdened, assuming you don't have any enchanted armor such as a Belt of Carrying. Although you can pick the bomb up and successively teleport with it to the lever's down staircases even when Overloaded, you must actually be able to pick it up and carry it at some point.