11. Manhattan, New York
One of the five boroughs of New York City, Manhattan is actually an island, bordered by the East River and the Hudson (and a little bit by the Harlem River). This island is a bit less than 23 square miles and is home to almost two million residents. Add in the daily influx of workers, and the island routinely holds close to four million people.
No other city in the world offers the frenetic energy of New York City. It's filled with the world's best shopping and dining, along with incredible museums.
Manhattan also has a giant green heart, Central Park. No matter the season, it provides a playground for the city's residents, offering a range of activities from museums to a zoo. There's also a lot of green space where you can play and relax, along with miles of running, biking, and skating trails.
12. Paris, France
No visit to the French capital is complete without a trip to and a trip up its most iconic structure. The 300-meter-tall Eiffel Tower was quite simply, the tallest man-made structure in the world, from its opening in 1889 for 41 years until 1930.
Use your visit as a stair workout and climb the 300 steps from ground level to the first of three levels on the tower. If you're in great shape, climb another 300 steps to the second level. Then hop on the elevator here to get to the top. Aside from the workout, you'll also skip most of the crowd who want to take the elevator the whole way.
13. San Francisco, California
San Francisco is a truly unique American city and one of the world's great vacation spots. Explore its hills, ride the cable cars that climb them, and eat some seafood at Fisherman's Wharf. Also spend some time exploring Marin County on the other side of the Golden Gate Bridge, including the picturesque town of Sausalito. The giant redwoods of Muir Woods National Monument are only 30 minutes away and also well worth a side trip.
Be sure to also make time for a visit to or even better, a drive across, the Golden Gate Bridge. This monument to modern engineering genius spans the strait that connects San Francisco Bay and the Pacific Ocean. The almost two-mile-long, six-lane bridge connects the Northern California city with Marin County.
Opened in 1937, the bridge has a unique, geometric beauty and can be viewed from many areas on either side of its span. Some of the best views are from the Marin Headlands, a hilly part of the Golden Gate National Recreation Area, a national park which includes areas on either side of the bridge.
14. Hong Kong
Asia's largest city can feel like an Asian Manhattan, with giant skyscrapers in a compact area and a serious focus on business. But venture deeper, and you'll find the city's unique mix of ancient Chinese culture and remnants of its British Colonial history as well. Gleaming skyscrapers are built with hand-assembled bamboo scaffolding in a fusion of new and old.
The city is divided into two main sections: Hong Kong Island and Kowloon, separated by Victoria Harbour. Take the Star Ferry across the harbor, still one of the great travel bargains, given the spectacular scenery on both sides. You can also venture into the more rural areas to discover the sparsely populated Outlying Islands, hiking trails, and beautiful beaches.
15. Marrakesh, Morocco
Start your Marrakech adventure in the Jemaa el-Fnaa, the main, open square in the Moroccan city. It's the gateway to the medina or old walled city. The square is like nowhere else in the world, presenting a constant show of humanity. There are musical performers, snake charmers, monkey trainers, amateur boxing matches, and transvestite belly dancers.
It's also a giant food market, as well as a giant antiques market and swap meet. You can even get a haircut or have some dental work performed. At night, there are fire performers, and an outdoor food fair is set up in the center, with rows of food stalls fronted by counters lined with chairs.
This exotic African destination is only a short flight (usually less than four hours) from most major European cities. As a popular getaway destination, there are frequent flights available. Accommodations range from riads, traditional houses remade into luxury boutique hotels in the medina to five-star luxury resorts just outside the city in an area called La Palmeraie.