Well...how long is a piece of string? Humans have been travelling for a long time. The Romans built spa resorts for the wealthy. Pausanias wrote the first 'travel guide' sometime in the 2nd Century, aimed at Romans travelling to Greece. Before that Herodotus wrote a History which in the 5th Century BC, and he clearly travelled for it, implying that travel and tourism was possible when he wrote it. Greek travel was based on the idea of xenia (guest-friendship) which was often hereditary - basically think of you travelling to Sweden and staying with the friends your dad made when he was there - but you could also rent rooms when you went to see the Olympics and other ancient games. It seems as if the Egyptians toured their own country and the surrounds from no later than 1500BC. There is a great book called Travel in the Ancient World by Lionel Casson which goes into the dangers of travel as well (pirates, kidnapping, being sold into slavery etc...).