There used to be a vertical sundial on the southwest facade of the northeast wing.

References:

1. Blog of the Museum and Gallery of Konavle, "Franciscan monastery in Pridvorje as the center of Konavle", link
2. Badurina, Anđelko (1996) "Franciscan monastery in Pridvorje", Proceedings of the Institute for the History of Art, 20, 123-131. link