Aguas Calientes, officially called Machupicchu Pueblo, sits in a narrow valley below the ruins of Machu Picchu, shaped almost entirely by geography and access.

Vienna has a long memory. Once the capital of the Habsburg Empire, the city still carries signs of its imperial past in its palaces, concert halls, and wide boulevards. Visitors can walk through the Hofburg complex, where emperors once ruled, or tour the opulent rooms of Schönbrunn Palace, which features 1,441 rooms and a maze in its gardens. But Vienna’s many historic buildings now house contemporary art museums, cafés, and institutions that reflect the city’s modern identity.

Verona is situated at a bend of the Adige River in northern Italy. It is hard to imagine that antique arts, monuments that date back to Roman times, and the shadows of the world's most famous tragic lovers can add up to a smiling, buzzing city. Yet they do, thanks perhaps to Verona's talent for melding her past and her present, her ancient and new so gracefully that everything blends in easy harmony.

Istanbul is a city built on layers of empire. Spanning two continents, it was once the capital of three major empires: Roman, Byzantine, and Ottoman. Visitors walking through the Sultanahmet district can witness this timeline firsthand, from the Roman-era Hippodrome to the Byzantine mosaics of Hagia Sophia, and the towering minarets of the Blue Mosque. At nearby Topkapi Palace, rooms still display the jeweled swords, ceremonial robes, and handwritten Qurans once used by Ottoman sultans.

Tajikistan, a landlocked country in Central Asia, is defined by its dramatic mountain landscapes, including the towering Pamir and Fann ranges. These rugged peaks and deep valleys create a striking backdrop for ancient Silk Road sites and traditional villages, reflecting the country’s historical importance as a crossroads of cultures.