By 40: Joshua Tree National Park, California
By 40: The Great Wall of China
The Great Wall of China is known as one of the most massive architectural feats in the world, spanning more than 13,000 miles (according to estimates from 2012) and taking more than two millennia to build. Legend holds that more than 400,000 people died during the construction of the wall and were buried inside, making the wall both a fascinating relic of the past and a monument of the great sacrifices made to complete it.
By 40: Havasu Falls, Arizona
The intense eight-mile hike it takes to get to Havasu Falls in Arizona's Havasupai reservation (in the Grand Canyon) makes it a wonder only accessible to those who are physically up to the challenge. Of course, you could always travel by helicopter or horseback, but part of the thrill of this mesmerizing crystalline waterfall is arriving hot and tired, ready for a refreshing swim.
By 40: The Taj Mahal, India
Built over a period of 17 years by order of Emperor Shah Jahan is the Taj Mahal—a white marble mausoleum for his beloved wife, Mumtaz Mahal, who died in 1631. The UNESCO World Heritage Site is a true world wonder, radiantly standing in the sun and glowing with the light of the moon. As one of the most famous tourist destinations in India, it's worth noting that the best time to see this magnificent structure is from October through March, when temperatures are cooler.
By 40: Jemaa el-Fna market in Marrakech, Morocco
Known as a "souk" (market), Morocco's Jeema el-Fna holds some of the most unique and beautiful treasures you'll ever find. Visit vendors selling fresh spices, homemade crafts, luxurious rugs, beautiful scarves and more, then stop at one of the many street food stalls to taste tantalizing Moroccan specialties like "khobz" (crusty bread) and "brochettes" (mini chicken kebabs). Want to travel the souk like a pro? Rent a rickshaw (a motorized or bicycle-powered taxi) to navigate the endless walkways and alleys.
By 40: Machu Picchu, Peru
The majestic Incan ruins of Machu Picchu are located high in the Andes mountains of Peru and worth the lengthy journey to get there. If you're fit, there's a four-day, three-night hike along the Inca Trail, but it's restricted to approved groups on sanctioned tours (meaning no solo hiking, sorry). For the rest of us, there's a train going directly to the site via three different cities: Aguas Calientes, Cusco or Ollantaytambo. Once there, marvel at the wonder of this 15th-century Incan citadel.
By 50: Tokyo's Tsukiji Market
Known as the largest fish market in the world (with a very famous tuna auction in the early hours of dawn), Tsukiji Market is a must-see for hungry travelers headed to Tokyo. Head through the main gate off Shin-ohashi Street to access the fruit and vegetable market as well as numerous (delicious) sushi counters where you can have a legendary sushi breakfast. Just come early! The freshest fish and liveliest stalls all open before 6 a.m.
