than from the fighting positions lower down. The bergfried usually also served generally as a fortified tower. Examples of very high bergfrieds were or are those at Rheinfels Castle (54 m) and the Osterburg (53 m). Additional chemins de ronde (walkways behind the battlements) could be built on the lower storeys of a tower (e.g. Bischofstein Castle on the Moselle). Stronghold and prison The solid construction and inaccessible elevated entrance of the bergfried made it a relatively safe repository within the castle. Here valuables could be stored, so that the tower took over the role of a stronghold. By the Early Modern Period at least, bergfrieds were being used as largely escape-proof places of custody for prisoners. In particular, the shaft-like cellars in the base of the tower were often used as a form of dungeon called an oubliette, which was only accessible through a narrow opening in the ceiling. However, this form of cellar was not necessarily intended for such use, but was a result of the overall engineering design of the bergfried. The thick walls used in the base only left a narrow, about 4-8 metre high, internal space that was usually covered by a stabilizing vault and was only accessible through a hatch at its apex. This design was also a result of the fact that the elevated entrance of the tower was located on an upper floor. Access to the oubliette through the hole (an angstloch or "fear hole") was almost always by means of a ladder or rope winch. Wall steps, like those found in the old bergfried of Langenau Castle, are a rare exception. The cellar in the tower base was used in different ways. In some instances it was used as a warehouse or magazine, so sometimes piles of round stones were kept here for use as projectiles during a siege. In a few cases, it was used as a cistern, but often the room remained unused. The blanket assumption in older literature and often also in tourism that the cellar space was used as the dungeon is thus misleading. Most reports of the incarceration of prisoners in the basement of a bergfried date to the late Middle Ages and early modern period; to what extent this was common before then, is uncertain. Often it is probably a later change of use, as was the case in many town wall towers and even