CNN compiled 25 of what we think are some of the most impressive engineering/construction achievements to date, taking into consideration the era in which they were built and the knowledge and materials that were available to the designers.
The Palm, Dubai, UAE There are several tour operators within Dubai offering boat tours of the Palm.
Aqueduct of Segovia, Segovia, Spain Segovia is an easy day trip from Madrid and can be reached by both train and bus.
Great Wall of China, China Beijing International airport is the closest airport to any point of the Great Wall of China -- it's just a short taxi ride to the section known as Badaling Great Wall and there are also regular bus services.
Taj Mahal, Agra, India There are regular bus and train services connecting New Delhi with Agra.
Trans-Siberian railway, Russia The full journey starts in Moscow and ends in Vladivostok, but passengers can join at numerous towns and cities en route.
Burj Khalifa, Dubai, UAE
The Burj Khalifa is located in downtown Dubai and is well-connected by public transport.
Akashi Kaikyō Bridge, Akashi Strait, Japan The bridge is a short drive from Kobe Airport.
White Pass and Yukon Route Railroad, Canada
Excursions start from Fraser, British Columbia. The nearest airport is in Vancouver.
Tokyo Sky Tree, Tokyo From Ueno Station (Tokyo Metro Ginza Line), transfer to the TOBU SKYTREE Line at Asakusa Station - the Skytree stop is a 14-minute journey.
A spacewalk outside the International Space Station was cut short Tuesday morning because of a slight malfunction with one of the astronauts' space suits, NASA said.
Teotihuacan, Mexico There are regular buses to Teotihuacan from Mexico City.
Panama Canal, Panama The Panama Canal is best explored by organized boat tour, but Panama City's Tocumen International Airport is the nearest airport.
Taipei 101, Taipei, Taiwan Take the Taipei MRT-Bannan Line to MRT Taipei City Hall Station. From there, walk towards Xinyi Road from exit number two to Taipei 101.
Grand Canyon Skywalk, Arizona, United States
It takes around two hours to drive to the Skywalk from Las Vegas. Organised tours which depart from the city are also available.
Shanghai World Financial Center, Shanghai The building is a 20-minute walk from Dongchang Road Pier. The nearest subway station is Lujiazui Station.
Millau Viaduct, Millau, France The nearest train station can be found in the town of Millau, which is well connected to cities and towns throughout France. The closest airport is Rodez-Marcillac -- a 25-minute drive away.
London Underground, London London's Heathrow Airport is connected to the London underground
Kansai Airport, Osaka, Japan Kansai International Airport is connected to most of the major international hubs. Osaka is two hours from Tokyo on the Shinkansen bullet trains.
Hoover Dam, Arizona/Nevada, United States The nearest airport is in Las Vegas, 32 miles away.
Great Pyramid of Giza, Egypt There are regular bus services from the centre of Cairo and it's also just a short taxi ride.
Golden Gate Bridge, San Francisco There are regular buses to the bridge from downtown San Francisco, Marin County and Sonoma County.
Eiffel Tower, Paris The closest Paris Metro station to the Eiffel Tower is Champ de Mars.
Confederation Bridge, Prince Edward Island, Canada Travel to Prince Edward Island by ferry from New Brunswick. Charlottetown Airport is the island's largest airport.
Colosseum, Rome There are regular buses to the site, and it's also possible to get there by tram -- look for the "Colosseo" stop.
CN Tower, Toronto, Canada
The CN Tower is in the heart of downtown Toronto.