About half of Armenia's area of approximately 29,800 square kilometers has an elevation of at least 2,000 meters, and only 3 percent of the country lies below 650 meters. The lowest points are in the valleys of the Aras River and the Debet River in the far north, which have elevations of 380 and 430 meters, respectively. Elevations in the Lesser Caucasus vary between 2,640 and 3,280 meters. To the southwest of the range is the Armenian Plateau, which slopes southwestward toward the Aras River on the Turkish border. The plateau is masked by intermediate mountain ranges and extinct volcanoes. The largest of these, Mount Aragats, 4,430 meters high, is also the highest point in Armenia. Most of the population lives in the western and northwestern parts of the country, where the two major cities, Erevan and Gyumri (which was called Aleksandropol' during the tsarist period), are located.

The valleys of the Debet and Akstafa rivers form the chief routes into Armenia from the north as they pass through the mountains. Lake Sevan, 72.5 kilometers across at its widest point and 376 kilometers long, is by far the largest lake. It lies 2,070 meters above sea level on the plateau. Terrain is most rugged in the extreme southeast, which is drained by the Bargushat River, and most moderate in the Aras River valley to the extreme southwest. Most of Armenia is drained by the Aras or its tributary, the Razdan, which flows from Lake Sevan. The Aras forms most of Armenia's border with Turkey and Iran as well as the border between Azerbaijan's adjacent Nakhichevan Autonomous Republic and Iran.

Climate: Temperatures in Armenia generally depend upon elevation. Mountain formations block the moderating climatic influences of the Mediterranean Sea and the Black Sea, creating wide seasonal variations. On the Armenian Plateau, the mean midwinter temperature is 0° C, and the mean midsummer temperature exceeds 25° C. Average precipitation ranges from 250 millimeters per year in the lower Aras River valley to 800 millimeters at the highest altitudes. Despite the harshness of winter in most parts, the fertility of the plateau's volcanic soil made Armenia one of the world's earliest sites of agricultural activity.