A gate tower (German: Torturm) is a tower built over or next to a major gateway. Usually it is part of a medieval fortification. This may be a town or city wall, fortress, castle or castle chapel. The gate tower may be built as a twin tower on either side of an entranceway. Even in the design of modern building complexes, gate towers may be constructed symbolically as a main entrance. The gate tower can also stand as a twin tower on both sides of a gate system. Gate towers are also used symbolically as the main entrance in the design of modern building complexes. The Kasselburg in Rhineland-Palatinate has a double tower gate tower, which was also used as a residential tower.