Šibenik's three fortresses are not interchangeable. If you want the easiest classic first visit, start with St Michael's. If you want the history explained most clearly, start with Barone. If you want the biggest panoramic payoff, start with St John's.
How to choose fast
St Michael's: best if your city stop is short and you want the cleanest old-town fit.
Barone: best if you want the defense story explained through the official augmented reality experience.
St John's: best if you want the highest viewpoint and a more committed hilltop visit.
What the official operator says
The official fortress operator currently lists regular opening hours of 9 AM to 8 PM, with last admission 30 minutes before closing. The official price page currently lists 11.50 euro single tickets and a 15 euro combined ticket valid across all three fortresses for 7 days.
Use the live official pages for hours, ticket prices, St Michael's, Barone, Barone AR, and St John's before you go.