Croatia also has Roman ruins, like this gateway in the town of Pula.
Croatia's natural wonders include waterfalls at Plitvice Lakes National Park.
Turkey has Roman ruins as well, including the intricate Library of Celcus in the coastal town of Ephesus.
The Turkish region of Cappadocia is known for cave dwellings intricately built into the landscape.
The ornate gate at the Dolmabahce Palace in Istanbul opens onto the Sea of Marmar, with Asian Istanbul right across the way.
The enormous Prague Castle incorporates many architectural styles and is even more striking when lit up at night.
Travelers have been flocking to the town of Karlovy Vary in the Czech Republic to take the waters for centuries.