Ginnyjo is correct. The Discover Tour Guide said that if we felt they did a good job we should leave a tip comparable to what a "pay for" tour would cost and he furthered explained that it should be around what you might pay for dinner. He also said this is his full time job and how he earns a living.

It's not a free tour unless you plan to not pay the guide. The paid for tours - some of which were inexpensive, were all better.

Ginnyjo - I'm sure some of the free tours can be enjoyable but not all and they aren't really free. I should have done sandemans but I was busy at 10am and discover started at 11am. The Third Reich Tour was excellent and cost just a little more than the free tour after tipping.

This is the Third Reich Tour I went on.

http://www.ww2inprague.com/