Tourism probably started in Roman times. Rich Romans visited friends and family who were working in another part of the Roman Empire. But when the empire broke down,this kind of tourism stopped. In the early 17th century, the idea of the "Grand Tour" was born. Rich young English people sailed across the English Channel .They visited the most beautiful and important European cities of the time, including Paris in France, and Rome and Venice in Italy. Their tours lasted for two to four years, and the tourists stayed a few weeks or months in each city. The "Grand Tour" was an important part of young people's education--but only for the rich. In the 18th century, tourism began to change. For example, people in the UK started to visit some towns, such as Bath to" take the waters". They believed that the water there was good for their health. So large and expensive hotels were built in these towns. In the 19th century, travel became much more popular and faster. When the first railways were built in the 1820s, it was easier for people to travel between towns, so they started to go for holidays by the sea. And some started to have holidays in the countryside as cities became larger, noisier and dirtier. Traveling by sea also became faster and safer when the first steamships were built. People began to travel more to far away countries. The 20th century saw cars become more and more popular among ordinary people. Planes were made larger, so ticket prices dropped and more people used them. Thus tourism grew. In 1949, Russian journalist Vladimir Raitz started a company called Horizon Holidays. The company organizes everything--plane tickets, hotel rooms, even food--and tourists pay for it all before they leave home. The package tour and modern tourist industry was born. The first travel agency in China was set up as early as 1949.But tourism did not take off until 1978.In 2002,the industry was worth 500 billion yuan and became an important part of China's social development. Modern tourism was born   _  .
in 1949 in Roman times in the early 17th century in the 19th century