When you travel to the Cappadocia region of Turkey you have to stay in a cave hotel. Sleeping in a room carved out of the area’s ‘fairy chimney’ rock formations is inherently cool. When you realize that your room is also literally cool—even in the midday heat—you suddenly have a better understanding of the clever ways people managed to live in a challenging environment for centuries. The hotel’s best feature might be the terrace, where you relax on pillows and eat a Turkish breakfast of apricots and yogurt as you watch dozens of hot air balloons rise from the valley below. From $76.