Lake Bled -- The iconic image of Slovenia: a turquoise lake with a tiny island church, backed by the Julian Alps. Rent a traditional pletna boat to the island, climb the 99 steps to ring the wishing bell, and eat a kremna rezina (cream cake) at the lakeside. Overvisited? Perhaps. Worth it anyway? Absolutely.
The Soca Valley -- The Soca River is an almost impossibly vivid shade of emerald green. The valley around Bovec offers world-class whitewater rafting, kayaking, and canyoning. It is also the setting of Ernest Hemingway's A Farewell to Arms and the site of fierce World War I battles, with an excellent museum at Kobarid.
Postojna Cave and Predjama Castle -- Postojna is the most visited cave in Europe, with a train ride into a vast underground world of stalactites and stalagmites. A few kilometers away, Predjama Castle is built into the mouth of a cliff cave and has been standing there since the 13th century. The combination of the two makes a superb day trip.
Ljubljana -- One of Europe's most charming small capitals. Ljubljana's car-free center is organized around the Ljubljanica River, lined with willow trees and cafe terraces. The hilltop castle, reached by funicular, provides views across the city to the mountains beyond. Architect Joze Plecnik's bridges, markets, and riverbanks give the city a distinctive character.
Triglav National Park -- Slovenia's only national park covers most of the Julian Alps, centered on Mount Triglav (2,864 m), the country's highest peak and national symbol. Hiking ranges from easy valley walks to serious mountain routes. Lake Bohinj, quieter than Bled, sits at the park's edge and is surrounded by pristine forest.
Piran -- A Venetian-flavored town on the Adriatic, with narrow streets, a church-topped promontory, and sunset views across the Gulf of Trieste. Piran is the highlight of Slovenia's short coastline and has the best seafood in the country.
The Vrsic Pass -- The highest road pass in Slovenia (1,611 m), with 50 hairpin bends climbing through the Julian Alps. The drive is spectacular, connecting the Soca Valley with Kranjska Gora. Stop at the Russian Chapel, built by Russian prisoners of war during World War I.
Ptuj -- Slovenia's oldest town, with a hilltop castle, a Roman heritage, and the Kurentovanje carnival in February, when people in sheepskin costumes with cowbells chase away winter. It is one of Europe's most unusual folk traditions.