This is the worst experience on Viator. The operators of this tour, Travel Insiders, are incompetent. It is not a guided tour at all but simply ordinary tickets (no skip-the-line, no guide) for the castle. The tickets for the Sisi Museum are included according to the description on Viator but Travel Insiders claimed to me that they were not included!! I
I had booked months in advance for 10 a.m. but the day before they told me that the 10 a.m. time slot was full but that noon was available. They also told me that only the castle operates by time slot. They finally ended up sending me tickets for the Museum after I proved to them that the tour included it, but the tickets were for 11 a.m. on the very day of the castle visit at noon. Even though this visit was supposed to be without a time slot! I finally bought tickets for the next day myself because the tickets purchased on Viator could not be transferred. I requested a refund for these tickets but I never received a response from Travel Insiders. Avoid them!