The ice temple is a location in Among Thieves. It is a massive temple constructed by the inhabitants of Shambhala, and only accessible through a large icy cave system in The Himalayas. The cave system is traversed during "Mountaineering", whereas the temple itself is explored during "Heart of Ice".
The temple's location was originally discovered by Karl Schäfer and his Ahnenerbe expedition, while they were looking for the entrance to Shambhala. The expedition made it all the way to the heart of the temple, where Schäfer's conscience caught up with him, and he executed the other expedition members. Seven decades later he sent Nate, along with Tenzin, to find the remains of his expedition, including the proof as to why Lazarević must not be allowed to gain access to the Cintamani Stone.
The two traveled through a cave system, during which they found a trail of remains belonging to the expedition, including rope ladders, crates, corpses, and two P08-9mm pistols. Partway through they also ran into the remains of a recently slain wolf pack, with Tenzin believing the attacked to be a ghost. He was later attacked by a yeti-like monster, until Nate managed to distract it with one of the P08-9mm pistols. Although he fails to kill it despite multiple headshots, Tenzin stabbing it in the back eventually forced it to flee.
Shortly after they discovered the ice temple proper and quickly learned they had to split up to be able to make their way through. The two made their way through the dilapidated temple, with Nate having a notably tougher time than Tenzin, until they gained access to the inner sanctum. There they discovered the remains of the expedition, and Nate learned that Schäfer must have had executed them all himself. A book Tenzin found taught him that they were part of the Ahnenerbe, and Nate came to the conclusion that Schäfer realized that full access to the Stone would have possibly dire consequences; based on the several monstrous statues holding a representation of the stone inside the temple, and the knowledge that ancient rulers already had become nearly unstoppable with only slivers of the Stone, alongside the appearance of the strange monster attack.
Nate and Tenzin's realization was cut short when they heard several growls, and decided they had to find a way out. After turning a lever that slowly started to lower an elevator two more monsters appeared, who started bombarding them with giant rocks. They barely managed to escape, with a monster lunging onto the elevator and almost dragging Nate off of it, although he managed to cause it to fall after shooting it, after which they managed to exit the temple safely.
The temple is located high up within The Himalayans, located inside a gigantic hollow cavern. Said cavern connects to a, still very large, series of ice-and-snow-covered caves, containing many seemingly bottomless depths. A large stone marker of sorts indicates the entrances of the cave, and also includes ancient Tibetan written warning for some sort of monster. The temple itself is mostly a hollow space, containing several pressure switches and levers, which activate various contraptions, often on the far side of the temple itself. Due to the remoteness, and difficulty of progressing through the temple, its exact purpose is unclear, other than an apparent symbolism as to the true impact of the Cintamani Stone on people.
The contraptions inside the temple include walls lowered by switches at the entrance, statue faces that extend out of the wall, rotating cylinders that hang from a ceiling, a large series of enormous rotating gears, what appears to be a giant flywheel, a lever-operated bridge made out of stone arms, and at the bottom end a group of smaller stone pillars, which culminate at a pair of switches that create a path to the massive statue at the far end of the temple.
The statue reaches all the way up the ceiling and holds a representation of the Stone, and will rotate to show a monstrous person holding the Stone instead once the path leading up to it has been activated. Underneath it is a small passage to the temple's inner sanctum, which includes several more stone statues worked into the walls, also of the same monstrous faces holding the Stone. It is otherwise entirely empty, with a simple lever being required to lower and raise an elevator to an exit high up in the ceiling.