Armenia is one of the most ancient states of Transcaucasia and the first country to adopt Christianity as a state religion. The centuries-old Christian traditions are depicted in numerous monasteries, churches and khachkars (stone sculptures with crosses carved on them), the most ancient of which date back to the 4th century AD. No less interesting are the ancient cities of the state, whose age reaches 3,000 years old, ancient fortresses and, of course, picturesque mountain landscapes abounding with deep canyons, turbulent rivers, waterfalls and lakes, among which is the largest Transcaucasian lake, Sevan.