The actual location of the city of Carcosa is difficult to determine, if, indeed, it has one single location at all. Carcosa is usually located on the shores of Lake Hali, or possibly Lake Demhe, sometimes described as lake-seas, and then only at certain times. These may be the ancient names for lakes that no longer exist in the same form. The nebulosity of Carcosa, both in location and nature, is one of its defining themes.