This was the first place we visited in Pula & we found it rather underwhelming. Apart from the views & a few cannons there isn't much else to see. You cannot see inside unless you pay to visit the Museum of Istria which is currently the main purpose of the Kastel interior.
There isn't any information about this Venetian Fort given outside so the visit is mainly for the views.
There are no toilet facilities without accessing the Museum.