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They're not necessarily the biggest. They don't have to be the oldest, or the tallest, or even the most expensive. But they're memorable. They're beautiful. They're unique.
When you travel there are man-made structures, buildings, statues and monuments, that – like the most stunning landscapes – will stick with you for the rest of your life. These are mine.
Taj Mahal, India
It's easy to be dismissive of the Taj because it's such a cliché – it's been photographed and visited and talked about so many millions of times before. But then you see it with your own eyes, and you understand what the fuss is about. A monument to love that easily lives up to its billing.
Hoover Dam, USA
To fly over the Hoover Dam is to understand in one dizzying snapshot the power humans have to alter their world. And this was built in the 1930s? It's a 220-metre concrete wall spanning the Black Canyon in Arizona, and it's a sight you won't readily forget.
La Sagrada Familia, Spain
Just when you think you can't face another cathedral, that you've seen all the vaulted arches and flying buttresses a casual observer can handle, along comes La Sagrada Familia and changes everything. Antoni Gaudi's still unfinished masterpiece is like nothing you've ever seen before, eccentric and daring and strange, and yet ultimately probably the most beautiful building in the world.
Great Pyramids, Egypt
These are another of those travelling clichés that live up to their billing, a truly incredible sight perched on the edge of the insanity that is Cairo. There's something pretty special about seeing in the flesh something you've gazed at so many times in photos, and still being impressed.
Burj Khalifa, UAE
It's not so much the view from the bottom that you'll remember, although the world's tallest building does look great from afar. The crazy thing is the way the world looks from the 124th floor of the Burj Khalifa – it's like a kids' toy, a plastic model replica of the real world, something that seems too far away, too abstract, to even be real.
Rock-hewn churches of Lalibela, Ethiopia
These don't get the same recognition as similar edifices carved from stone in Petra, Jordan, but this network of 11 churches, each hewn from living rock in the highlands of Ethiopia, is equally impressive. Just getting there to see them is an adventure you won't forget; walking through the cool, dark churches is another thing entirely.
Machu Picchu, Peru
Machu Picchu would be memorable if it was just sitting on a plain somewhere at sea level. But the fact these Incan ruins are perched high up in the snow-capped Andes, clinging to a mountain-top surrounded by steep drops and soaring peaks, makes them even more memorable. Another one that lives up to the hype.
Leshan Giant Buddha, China
Legend has it this 71-metre-tall stone Buddha was carved at the confluence of three rivers as a way to protect boats sailing through the treacherous waters below – and it worked. The huge amount of rock chiseled from the cliff is said to have altered the flow of the rivers themselves, making it safe for all to pass. Whether that's true or not, this statue in central China is still one impressive sight.
Ta Prohm, Cambodia
Everyone goes to Siem Reap to see Angkor Wat, and everyone leaves talking about Ta Prohm. This is the temple you've probably seen all the pictures of, the building that's been left at the mercy of nature, with huge trees growing out of its crumbling rock walls. It makes you feel like Indiana Jones just being there. If it wasn't so insanely popular with other tourists it would be perfect.
Naqsh-e Jahan Square, Iran
One of the best experiences you can have while travelling is simply perching yourself on a stone seat in Esfahan's main square and watching an entire evening go by. Surrounded by arched walls dotted with mosques and teashops, this is where the city's residents come to play, to socialise, to shop and to chat among its pathways and gardens. It's beautiful.
Memorial to the Murdered Jews of Europe, Germany
It's controversial, this monument, which is maybe what makes it so memorable. How do you capture the horror of the Holocaust, how do you sum up with bricks and concrete the violent death of so many innocents? In Berlin they've chosen to do it with a series of plain, blank, grave-sized concrete blocks. If nothing else it makes you think, long after you've left the city.
Fez medina, Morocco
There's nothing beautiful about the labyrinth of alleys and shops that make up Fez's medina, nothing contemplative or serene. It's bonkers in there, a rush of tourists and shoppers, donkeys and horses, spices and slabs of slowly rotting meat. But that doesn't mean it's not memorable. There's nothing quite like the Fez medina anywhere else in the world.
Genghis Khan statue, Mongolia
So there you are, cruising the Mongolian steppe in a clunky old Landcruiser, rumbling along empty roads, looking at endless plain after endless plain, when suddenly, there on the horizon appears the biggest goddamn statue of a guy on a horse that you've ever seen. This is the Genghis Khan Equestrian Statue, a 41-metre-high silver colossus depicting one of history's most savage leaders atop a big horse. Of course.
Wat Rong Khun, Thailand
Like Sagrada Familia, this is one for those who think they're all "templed out" after having been dragged past every pagoda and stupa in South-East Asia. Because the "White Temple" in Chiang Rai is something else, a sometimes-bizarre edifice in the middle of a lake, where ghoulish hands reach out towards people entering the building, and an image of Death welcomes them further in.
What are the most memorable man-made structures you've ever seen?
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