The mainland of Greece is a mountainous region that forms the largest part of the country. It is bordered by the Aegean Sea to the east, the Ionian Sea to the west, and the Mediterranean Sea to the south. The mainland includes several important cities, such as Athens, the capital, and Thessaloniki, the second-largest city. The landscape is characterized by rugged mountains, fertile plains, and deep valleys. The Pindus mountain range runs through the center, while the Peloponnese peninsula lies to the southwest. This diverse geography contributes to Greece's rich history and cultural heritage.