Next time you visit Sozopol, pay more attention not to the quaint houses in the Old Town, the beaches around or the quality of food and service in the restaurants. Instead, take a stroll by the sea and take in... the rocks.

The rocks were in actual fact essential for the creation and survival of Sozopol. The town appeared in the 7th century BC when a group of Greek colonists decided the narrow, rocky peninsula at the southern end of the Bay of Burgas would be a safe and convenient place to settle in and conduct business from. Almost three millennia later, this peninsula remains the core of Sozopol.

Its rock were formed millions of years earlier, as the result of the volcanic activity that created the eastern part of the Strandzha mountain range. Wind, waves and sun gradually carved some of them in spectacular shapes all over the Bulgarian south Black Sea coast. One of the most intriguing of these is right in Sozopol.

Located by the seaside promenade at the northern part of the Old Town (the one without a fake ancient fortress wall), the Palikari Rocks are one of the symbols of the city. Their name means a boy in Greek, the language that from Sozopol's foundation until the state-organised population exchanges in the 1920s used to dominate the local soundscape.

The story of a local boy who loved diving from the rocks, and exploring an underwater cave beneath, explains their name. One day a storm arose, and the boy was trapped in the cave, never to resurface. In Greek, palikari means boy, or a strong and adventurous man.

If you know from where and when to look at the Palikari Rocks, you will discover that they quite convincingly resemble the Easter Island moai, or stone heads.

This is probably why some people have endorsed the idea that the rock was not formed naturally. Instead, they claim, it is a part of a large rock shrine built by... extraterrestrials.

The Palikari rocks are easy to get to. Just walk down the steps from Morski Skali street and you are there. There is no ideal time to photograph the Palikari as they look different at the different times of day. For a start, try late afternoons or early evenings. Bring a sturdy tripod and beware of slippery surfaces.