Now it is hard to visualize a map that does not feature north at the top, but this was not always so.

The oldest known map in the accepted sense of the word was drawn about 3,800 BC, and represents the river Euphrates flowing through northern Mesopotamia, Iraq. This, and others that followed it, were little more than rough sketches of localized features; it was not until many centuries later that the ancient Greeks placed the science of map-making on a sound footing.

At the fore front of the pioneers in the field was the Greek mathematician and philosopher Claudius Ptolemaeus (c. AD 90~168), more popularly known to history as Ptolemy. The last great scientist of the classical period, he was the first to draw a map that was based on all available knowledge, rather than guess or imagination. Earlier, the Babylonians had attempted to map the world, but they presented it in the form of a flattened disc rather than a sphere, which was the form adopted by Ptolemy.

Given the state of knowledge of those times, he got things wrong; for example, his estimate of China and the Atlantic Ocean was far from being accurate. Nevertheless, it was a useful effort, and the map remained a word of reference for over a thousand years. In fact, Christopher Columbus used a version of it when he set sail in search of the New World - which caused him some navigational problems, since Ptolemy had calculated wrongly the size of the Atlantic and was unaware that the Pacific Ocean existed.

The really important thing about Ptolemy's map was that north was at the top. The reason for this was that he decided to orientate the map in the direction of the Pole Star since Polaris was the immovable guiding light in which the voyagers of that era placed their trust.

North at the top remained the accepted arrangement until the early Middle Ages, when the Church began to interfere seriously with the advance of science. In accordance with the orders of the Church, maps were still produced in accordance with Ptolemy's principles - but now Jerusalem was the central feature, as it was held to be the center of the Christian faith, and east was moved to the top.

These maps are often called "T" Maps because they show only three continents - Europe, Asia and Africa - separated by the "T" formed by the Mediterranean Sea and the River Nile. From a navigational point of view, they were almost useless.

More accurate maps began to appear in the 14th century, with the spread of trade and increasing reliance on the compass. Once again, north assumed its rightful place at the top of maps.