Nilometer

The new road comes close to the ancient city’s commercial districts, its harbour walls and the former site of an ancient Nilometer, used to measure the height of the annual flood, said David Jeffreys, a British Egyptologist who has been working on Memphis for the Egypt Exploration Society since 1981.

At its southern tip, though, there survives a Nilometer built in the ninth century — a structure that measured the river’s seasonal flooding and thus predicted the annual harvest.

Using records from Cairo’s Nilometer — an octagonal marble column that was used for recording Nile flood height from 622 to 1902 A.D., the team found that flooding tended to be weaker, or entirely absent, during years when there was a large volcanic eruption somewhere in the world.

I made a beeline for the Nilometer, a 9th-century tool that gives insight into the crucial role the Nile played in the health and productivity of the city.

The Nilometer building houses a big pit that plunges deep below sea level, connected to the river through a system of tunnels.