We did the Free tour with Bianca on 16-Jul and the paid Castle tour with "George" ( his English name) on 17-Jul. Both tours were extremely good, informative and gave a quick overview of the city and its history and helped us plan our rest of the day better. The guides were very enthusiastic and answered all our questions. Really good way to get to know Prague quickly. Most people were happy with the tour demonstrated by the generous tips at the end of the Free tour. Keep it up!