It is a little weird, but it is not free to get on the bastion itself to see the views of Budapest. I don’t remember the price, but it is not expensive. When we went, we barely got there on time (the cash desks closed at 16:00), so beware!
St. Stephen’s Basilica, Budapest Parliament, Holocaust Victim Monument - Shoes on the waterfront, Szczecin Chain Bridge, Buda Castle, Castle Quarter, Fisherman's Bastion, funicular, and zero kilometers, as well as breakfast lunch and all sorts of goodies in different places. It was an excellent adventure!