Warp gates (Soul Reaver)

Warp gates were the method of transportation that Raziel used to get across Kain's Empire. The only drawback though, was he could only travel to gates he had already been to. It is unknown who constructed these machines but they appear to have an image of a specific territory with each individual gate. They may have been constructed by human slaves in Kain's empire (seeing as how the human citadel has one as well, perhaps after a revolt and reclaimed their territory from Kain's rule) and there is also the warp gate in the abyss caverns (how it got there is unknown).