Built by Gustave Eiffel for the 1889 World Fair, held to commemorate the centennial of the Revolution, the Eiffel Tower (Tour Eiffel) made headlines at the time as the world's tallest structure at 1,050 feet (320 meters). Initially opposed by Paris' artistic and literary elite, the tower was almost torn down in 1909, but its salvation came when it proved an ideal platform for the antennas needed for the new science of radiotelegraphy. Today, the highlight of a visit is the supreme view over Paris. When you're done peering upward through the girders from the ground, head up to the three levels open to the public, one of which features the famed 58 Tour Eiffel Restaurant. Just southeast of the Eiffel Tower is a grassy expanse that served as the site of the world's first balloon flights. Today, the area is frequented by skateboarding teens and activists stating their views on the current state of France.

Located in the beautiful and iconic Sydney Harbour, the Sydney Harbour Bridge overlooks the magnificent blue waters that help to make the Harbour a spectacular sight. Nicknamed "The Coathanger" because of it's steel arch-based design, the Harbour Bridge boasts 8 traffic lanes, 2 railways and a pedestrian and bicycle lane, transporting both locals and tourists from the Central Business District (CBD) to the North Shore. Visitors interested in getting the best view from the bridge can do so with the help of the BridgeClimb. Climbers can choose to climb either the outer arch or the inner arch of the bridge for spectacular views and an unforgettable experience. The bridge also plays a special part in the annual New Year’s Eve fireworks displays, where hundreds of spectators travel from near and far to gather on the shore and on the water to watch the festivities each year.

One of the world’s greatest unsolved mysteries, people have speculated about Stonehenge for centuries, wondering who built it, why, and how. The circle of massive standing stones in the middle of a green field is about 3500 years old, and will perhaps forever remain enshrouded in mystery, making it an even more intriguing place to visit. Check out the impressive structure and hear the various theories that have evolved regarding Stonehenge.

La Sagrada Familia is no doubt the most iconic structure in Barcelona. The church, located in L'Eixample, has been a fixture in Barcelona since construction commenced in 1882 and as building continues on today the structure's fame only grows. Though still a work in progress, the church already is an amazingly intricate structure. Antoni Gaudí spent 43 years on this project and, since his death in 1926, the duty to finish it has been passed on to several architects. Though the responsibility continues to change hands over the years, the architects have all respected Gaudí's vision and have made additions with his design in mind. Inside the church has an impressive stained glass windows line the main room and a lift takes visitors up one of the towers to enjoy the view. Smaller rooms hold exhibits detailing the history and future of the structure. La Sagrada Familia is projected to be completed in 2026, the 100th anniversary of Gaudí.

The Blue Lagoon is a unique wonder of Iceland, a result of all that volcanic activity the small island is so famous for. In the middle of the weird and wonderful, flat black lava fields of the Svartsengi National Park, the huge, outdoor lagoon is filled by naturally heated geothermal water which comes from 6,500 feet (2,000 meters) below the surface of the earth. It is full of minerals, silica and algae and is especially good for the skin and relaxation. In fact, part of the Blue Lagoon development is a health clinic specializing in cures for psoriasis. The water is almost startlingly blue in color, and the white of the silica on the black lava rocks around the edges makes an amazing contrast. As well as soaking and swimming in the pool, the Blue Lagoon offers in-water massage treatments, saunas and steam rooms, and a cafe. On any visit to Iceland a few hours soaking in The Blue Lagoon is essential, and its location between Reykjavik and the airport makes it easy to do.

For almost 150 years, Alcatraz has given the innocent chills and the guilty cold sweats. Over the years it's been the nation's first military prison, then a forbidding maximum-security penitentiary, now a National Park. No wonder that first step you take off the ferry and onto 'The Rock' seems to cue ominous music: dunh-dunh-dunnnnh! The trip to Alcatraz is popular and space is extremely limited. Purchase Alcatraz tickets as far in advance as possible, up to 90 days. The roster of Alcatraz inmates read like an America's Most Wanted list. A-list criminals doing time on Alcatraz included Chicago crime boss Al "Scarface" Capone, dapper kidnapper George "Machine Gun" Kelly, and hot-headed Harlem mafioso and sometime poet "Bumpy" Johnson. Though Alcatraz was considered escape-proof, in 1962 the Anglin brothers and Frank Morris floated away on a makeshift raft and were never seen again. A visit to Alcatraz is more than just seeing the inside of an old prison.

The Statue of Liberty is one of New York City's (and the USA's) most iconic attractions. The monument was a gift from France in 1886, celebrating the 100th anniversary of the signing of the Declaration of Independence. The statue is 151 feet (46m) tall and stands, fittingly, on Liberty Island at the mouth of New York Harbor. Lady Liberty welcomes visitors and immigrants with the famous words, "Give me your tired, your poor / Your huddled masses yearning to breathe free."

The Grand Canyon Skywalk is a glass, 70-foot long, open-air bridge suspended 4,000 feet above the canyon floor, providing 720-degree views. The Skywalk is operated by the Hualapai Tribe, which owns and protects more than one million acres of land throughout the Grand Canyon’s western rim. Even with its remote location some 120 miles from Las Vegas, you can easily experience the Grand Canyon Skywalk on a day trip or overnight excursion to the West Rim.

The world’s famous Colosseum was built in 80 AD for the Roman emperors to stage fight to-the-death gladiator battles and hunt and kill wild animals, whilst members of the general public watched the violent spectaculars. Entry was free, although you were seated according to your social rank and wealth. Gladiatorial games were banned in 438 AD; the wild beast hunting continued until 523. The Colosseum is amazing for its complex and advanced architecture and building technique. Despite being used as a quarry for building materials at various points in history, it is still largely intact. You can see the tiered seating, corridors and the underground rooms where the animals and gladiators awaited their fate. Today the Colosseum has set the model for all modern-day stadiums, the only difference being today's teams survive their games.

The holy grail for lovers of Inca monuments, the enigmatic lost city of Machu Picchu is the most famous archaeological site in all of South America. The spectacular collection of temples, terraced hills and plazas was the mountain-top citadel of the Inca under Pachacutec and Tupac Yupanqui, until the coming of the Europeans with Pizarro. It may have the most familiar name, but Machu Picchu has refused to reveal many of its mysteries, including the secrets of its construction, function and demise. The overgrown ruins were discovered by US historian Hiram Bingham in 1911, and the quality of the stonework hints that it was an extremely important ceremonial site. The remains are thought to date from around 1450, built at the height of the Inca Empire, and as they escaped being plundered by the Spanish they include semi-intact icons and shrines that were defaced or removed at other sites.