Oval and approximately 20 feet wide, they initially look like gigantic mirrors, but better resemble a pin-sharp video screen once encountered up close.
Problems were encountered in building the foundations, accidents occurred, and the construction of the bascule (or drawbridge) span was complex and lengthy.
Whenever excrescences are encountered, an initiating and an exorcising amulet are placed over them, then they can no longer conceal or transform themselves.
