...as a day-trip from Prague.
We walked from the train station to the Ossuary, which was easy. My wife and I had hoped to take the 'tourist van', parked outside the Ossuary, to the cathedral/town. However, they need at least 3 riders before it goes. They offered us the choice of paying for 3 (105 CZK) but we decided to walk instead.
BAD IDEA. Your available energy is precious - don't squander it by doing this long, mostly uninteresting walk. Take the shuttle. Enjoy the Mine tour and other sights, then take a taxi back to the train station. You're on vacation.