Nilometer of Roda Island

At the southern tip of Roda Island stands a ninth-century Nilometer, a device built to measure the height of the annual Nile flood on which the country's harvests and taxes depended. A deep stone shaft holds a central graduated column, reached by a staircase spiraling down the walls, which are inset with pointed niches and inscriptions. The measurements taken here once determined official proclamations of a good or poor year. Sheltered beneath a later conical roof, it is among the oldest surviving Islamic structures in Egypt.