What to see in Bulgaria: 9 must-sees

Immerse yourself in the oldest capital in the Balkans, where 24 centuries of history pile up like the layers of an onion, from the 6th-century BC Thracian fortress to the glass skyscrapers that 21st-century ecohydrogeology has raised beside the Ottoman minarets. Sofia was founded as the city of Serdica by the Thracians in 500 BC and became the capital of the Bulgarian Empire (893-1396), when it was one of the richest cities in Europe. Tour the Alexander Nevsky Cathedral (1882-1912), the largest Orthodox church in the Balkans, where 700 kilos of gold cover the interior walls; admire the Blue Mosque (15th century), the only synagogue in the Balkans to have survived the Holocaust, and St. George Basilica (4th century), where Roman ruins mingle with Christian mosaics. The Baths Quarter, with its 45 minarets, 150 churches and 120 synagogues, is testimony to the coexistence of Ottomans, Slavs and Jews. Don't leave without trying rose yogurt at the downtown markets.

Explore the world's sixth-oldest continuously inhabited city, where 8,000 years of history are stacked on a hill where Thracians, Greeks, Romans, Byzantines, Ottomans, and Bulgarians have all left their mark. Founded as Eumeneia in the 4th century BC, Plovdiv was the capital of the Roman province of Thrace and today preserves the 2nd-century Roman Theatre (7,000 spectators), the Roman Stadium (3,000 meters), the Aqueduct (3rd century), and the Thracian Ecbatana. Wander the Old Town, where 18th-century Ottoman wooden houses with pastel-colored facades rise over Kaleto Hill; admire the Dzhumaya Mosque (1585), the Church of Saints Constantine and Helena (1848), and the Tach Bazaar Market, where fruit and spice vendors create a spectacle of color. The Roman Theatre, restored in 1981, still hosts concerts and plays in summer.

Behold the 13th-century frescoes that experts consider the transition from medieval art to the Renaissance — 240 figures narrating the life of Christ with a naturalness that anticipated Giotto by 100 years. The Boyana Church, declared a UNESCO World Heritage Site in 1979, houses 240 figures painted between 1215 and 1259, including the portrait of Kaloyan and the Virgin and Child, which show a realism unprecedented in European medieval art. The frescoes, discovered in 1912, revolutionized the history of art by demonstrating that Bulgarian painters were already using perspective and chiaroscuro 100 years before the Italians. The church, surrounded by a 7-hectare garden where 300 plant species create a green oasis, admits only 50 visitors a day to protect the frescoes from light and humidity.

Discover Nessebar, the Mesambria founded by the Greeks in 560 BC on an 800-meter peninsula linked to the mainland by a 6th-century causeway. Greece, Rome, Byzantium, Genoa, Venice, and the Ottoman Empire all left their mark over 3,000 years. It preserves 40 Byzantine churches from the 14th-15th centuries, the largest concentration in the world: visit Saint Stephen and its frescoes, Saint Paul, and the Archaeological Museum with a bronze statue from the 8th century BC. Wooden houses with balconies overlook the main street, and restaurants serve Black Sea fish facing the Strandzha Mountains.

Take in the 47 glacial lakes of Pirin National Park, a UNESCO World Heritage Site since 1983, where Mount Vihren rises to 2,914 meters over 26,000 hectares. Follow trails past waterfalls and forests of Pinus heldreichii, a pine that has existed for 20 million years, and at dawn look for Badger Lake, Nereid Lake, and Emperor Lake. The park is home to 1,600 plant species, 200 bird species, and 58 mammal species, including 220 brown bears and 60 lynxes.