How would we travel without maps? It would be a bit adventurous (冒险的) to set off from Oxford University to go to London Bridge if there wasn't a map of the London Underground at each station. In fact, a lot of the early map-makers were adventurers and explorers, especially in the 15th and 16th centuries. So what did people do before there were maps? Well, it was quite easy to use natural signs like mountains and rivers if you were travelling on foot or riding a horse. People took small boats down rivers and followed coastlines. And it was much more logical (合理的) to use time, not distance, to measure (计量) journeys: the next village is a three-hour ride, for example. In fact, in the earliest maps, people didn't draw landmarks. They drew the stars. It was very easy to see the night sky and use it for navigation (航行). The sky was a lot clearer before the light pollution from cities that we have today. When towns and cities were built, people drew road maps which gave correct distances and directions. The London Underground was opened in 1863 and it also used a road map style. But a man called Henry Beck realized that travelling by train wasn't the same as driving your car across London. Passengers only needed to know which stations to change at. His new design (设计) for the Underground map wasn't very popular with the train companies at first. But the passengers loved it and in 1933, 700,000 copies were printed. These days, of course, you can ride a bike, drive a car or go through a forest and know where you are exactly, using a GPS. It's really difficult to get lost!