Although it’s based on a mass-appeal trend, it’s worthy. This well-assembled tour dispenses reams of Harry Potter trivia, from the books to the movies and locations from the movies. Groups of 20 start at London Bridge, near Borough Market, and wind up in Leicester Square. Because so much London history is folded in, there’s enough for non-Potterheads. Book online. Tours are 2 1/2 hr.