The Rotonda is the unofficial name of the remains of a small church located on the slopes of Utrk Hill, which descends towards the Mali Ston Bay. The Rotonda is located next to the small village of Ošlje, near the border with Bosnia and Herzegovina, in the area of the municipality of Dubrovnik Primorje. Ošlje used to be one of the larger inhabited places, and certainly one of the oldest, as it was mentioned already in the 10th century. Ošlje today has only a few dozen inhabitants.

The church itself is full of mysteries. It is a building of which there are very few in the world, while the Rotonda is one of two such in Croatia - a circular floor plan with eight apses on the outside and inside. The apse is a semicircular area of the church surmounted by a semi-dome. The Rotonda in Ošlje has no preserved vault or dome and is generally poorly preserved. Its research began in the 1950s, when the first conservation measures were carried out on the church, however, until today, the Rotonda has remained quite hidden from visitors, scientists and researchers. That's why we don't even know when it was built, but it is assumed that it was in the 10th century. We don't even know what the church was called because there are no preserved traces of it. We don't even know who built it or for what purpose, but we assume that it was a private adventure of one of the rulers at that time.

The Rotonda is so unique and unexplored that it is hidden from casual travellers. The locality is called Bijela lokva (“White puddle”) by the locals because of the nearby watering hole. The Rotunda can be reached by car, and then you can walk freely in the surrounding greenery bordered by dry stone walls and take fascinating photos of this old building, which looks spectacular from the air. The walls of the Rotonda are one meter thick and two to four meters high. The total circular interior space is a little over six meters. The construction itself is simple, rustic. Thick, broken stone chiselled in parts where necessary.
The Rotonda stands in its uniqueness and secrecy on the green slopes, itself also surrounded by vegetation, which is not resisted even by the walls of this truly valuable and important building.

FUN FACT: The Rotonda is attracting more and more attention from many researchers because it possesses certain acoustic properties, which allow sound to remain inside, while outside sound is reflected.