More than two thousand years ago, in 360 BC, the Greek writer, Plato, described a beautiful city. He said that it was lost somewhere under the ocean. He called this city Atlantis. This was the beginning of the legend(传说) of Atlantis.
Plato said that the people of Atlantis had been rich and happy. There were amazing palaces and ports in the city. The houses had fountains with hot and cold water, and the walls were covered with silver and gold. Farmers grew food for all the people outside the city. It was sad to think that no one would go there again.
For two thousand years, everybody thought that Atlantis was just a fantastic story. They thought that Plato had invented it. But then in 1882 an American called Ignatius Donnelly wrote a book about Atlantis. He believed that there was really a beautiful lost city under the ocean. Thousands of people read his book and wanted to find the lost city.
A lot of people believed that Atlantis was on an island in Greece called Santorini. Santorini used to be much bigger than it is today. About 3,500 years ago, a huge volcano (火山) erupted(爆发) and most of the island sank under the ocean. Some people say it was in Spain, Asia or even in England. People have been looking for the lost city for more than a hundred years, but nobody has ever found it.