A drop tower or big drop is a type of amusement ride incorporating a central structure or tower. Drop towers vary in height, passenger capacity, lift type, and brake type. Many are custom-made, although there are some mass-produced designs. Riders experience free-fall initially, followed by rapid heavy deceleration.With most drop towers, a gondola carrying riders is lifted to the top of a large vertical structure, then released to free-fall down the tower.