Lotrscak tower Zagreb is a must. You can visit by funicular. It will cost you 20 Kn (adult) and 10 Kn (child) to get to the top of the tower. It is also an opportunity to discover temporary exhibitions but the highlight is the view on the main points of interest such as the Zagreb Cathedral, the Funicular, St. Mark Church, the National Theater.
Be careful, at noon a cannon shot is fired from the tower! The opportunity to set your watches or check your heart condition.
Price : 20 Kn (adults) 10 Kn (children).Source