The walls of Ostrovica tell a legend of a woman walled-up alive there. The legend says....
Once, as the thick walls of Ostrovica burg were being built, there were numerous strange occurrences happening. Everything that had been built over a day would lie in ruins after the following night. One of the desperate masons than dreamt a most peculiar dream. In his dream he saw nymphs destroying everything builders had built. The nymphs also said they call for an offering in the form of a woman who would be walled up alive, after which they would stop destroying the burg.
The very same day after the builder had dreamt the daunting dream, he and his fellows abducted a woman who had brought them the food and walled her up alive in the walls of the burg. As the woman was a young mother and had still been nursing a baby, milk from her breast started seeping through the cracks of the wall. The markings from her milk can still be seen beneath the thick walls of Ostrovica burg even from Kulen Vakuf.
For a long time the marking was believed to be petrified milk from the poor woman and therefore women who could not have children from the area would often make pilgrimage to this burg, scratch the grey-white powder from the stone and make potions for fertility.
However, the scientific explanation of this several meters long and a few centimetres wide marking is more realistic and sensible. It is a common phenomenon in kasrt landscape called moonmilk or cave milk which is actually a precipitate from limestone and it truly resembles milk with its white creamy substance.