The Nilemeter of Roda Island, which was used to measure the flood levels of the Nile River, is considered to be one of the oldest structures that dates back to the period just after the Arab conquest of Egypt. It is known in Arabic as the Miqyas (Miqyas El-Neel). It is situated on the southern tip of the island of Roda. In this location there are some evidences that other Nilemeters since the Pharaonic Period. The existing Nilemeter dates back to the time of the Abbasid Caliphate al-Mutawakkil about 861AD. It remains mostly original, except for the wooden conical roof (domed on the inside) which is a modern restoration. It was designed by Abu El-Abbas Ahmad ibn Muhammad ibn Kathir al-Farqhani (known in the West as the astronomer Alfraganus.) This Nilemeter consists of a pit that goes down into the water of the Nile. Three tunnels lead into it from the river at different levels. In the center of the pit, there is a column graduated into sixteen cubits. The upper tunnel is the widest of the three levels. Around the pit, one can notice the impressive Kufic inscriptions for some verses of the Holy Quran about crops, rain, and abundance.