Received my confirmation for the Bulgaria in 12 Days tour. Early September 2022. Debating how many nights I might book in Sofia before the RS tour begins. One night or two. Any suggestions on a day trip from Sofia to a site not visited on the tour? I won’t have a car, so anything distant would be some type of tour/excursion. Or any “must see” site in Sofia that is not on the tour, or something that might warrant more time than given on the tour?