The free tours or walking free tours are walks that are done on foot, in small groups in the company of a host, through the historic centers of the cities. The latter is also variable because more and more cities are incorporating it, although they are not the most touristy, and because there are more and more options to get to know not only the historic center of the cities but to dare to go a little further.
In general, free tours or free tours last between 2 and 3 hours and have a historical stamp, because the host usually emphasizes the monuments, curiosities, or historical facts of each site.
Those interested have to enter the web and reserve the place. In that same reservation, they are told the meeting point.
The amount of tip (money) you leave on a free tour depends on each one and is a very personal decision. In general, the hosts are usually very good, they add a lot of fun to the journey and tell really interesting things. So it's a good experience and worth acknowledging, the average starting at $ 5.