Ostrov is a commune in Tulcea County, Northern Dobruja, Romania. It is composed of two villages, Ostrov and Piatra. It is the site of the Rom…Ostrov is a commune in Tulcea County, Northern Dobruja, Romania. It is composed of two villages, Ostrov and Piatra. It is the site of the Roman fort Beroe in the Roman province of Moesia and part of the defensive frontier system of the Limes Moesiae along the Danube.