Worth a visit... Absolutely Ticket situation... Crazy Firstly, yes you really must make time (40 minutes) for a visit here. Amazing history, great talk from the guide and amazing views from the top of the tower. There is very limited access to the Baroque Library and you aren’t allowed to take photos either. Everywhere else you are free to take photos. There are a number of original pieces of astronomy equipment from the time of Johannes Kepler. Be warned that there are 172 steps to the top of the tower and most of these are on a very tight spiral staircase. The ones that aren’t are on old uneven wooden stairs from 1722, not surprisingly the consideration to health and safety is next to none. At the time we were there the lift was not working so this is only for someone with fairly good fitness and mobility. So with all that out of the way, yes, you really should go. Now to the tickets... There is nowhere online you can buy tickets, you must go to the ticket office at the entrance to the museum. There will probably be a queue, this may be people waiting to buy tickets or people queuing for the next session. With a 25 person limit for each session these sell out quickly. We got there at 10:00 (when they open) and the next available time was 13:30 all the earlier ones had been sold the previous day.