You have to pay to visit the very small monastery which you enter on the long flight of stairs to the left of the chapel (which is reached through steep steps and is only open during service). The entry fee is cheap (5 kuna I think). the most interesting part is the little museum they have which houses some quite nice paintings and interesting reliquaries including skulls.
If you were only going to visit one of the monasteries in Dubrovnik I would recommend for this one.
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