The Russian fortress Bomarsund is one of the most important historical monuments of the Åland Islands. Its ruins are located 25 km from Port Maria in the city of Mariehamn, in the municipality of Sund. The Russian Empire began construction of the fortress on the Åland Islands, which it owned at the time, in 1832. However, the work could not be completed: in 1846, construction was halted due to the fortress being put on military alert, and in 1854, during the Crimean War, the fortress was completely destroyed as a result of an Anglo-French attack. The main fort of the fortress was built on Åland Island over 12 years. In addition to it, 14 defensive towers were planned, of which only three were completed by the beginning of the Crimean War. Interestingly, the construction of Bomarsund involved not only soldiers but also convicts. Since prisoners often attempted to escape, local residents earned significant income from capturing them.

On the territory of the fort, an Orthodox church was built, a garrison town was located near the fortress, and a hospital and storage facilities were erected on Presto Island. However, before the attack, all the buildings were burned by local residents to prevent the enemy from using them during the battle.

Today, only ruins remain of the powerful bastion, but the fortress continues to attract tourists from around the world as one of the most interesting attractions of the Åland Islands.

The red bricks left from the destroyed walls of Bomarsund were later used in the construction of many structures, including the Orthodox Uspensky Cathedral in Helsinki. Only a few cannons and fragments of the fortress walls remind us of the scale of the battle that took place on the island. The most picturesque views of Åland can be seen from the ruins of the Nutvik tower. Not far from the fortress, on the other side of the rocky passage between the islands, is the Bomarsund Museum.