
The Great Wall of China is one of the world's most iconic tourist destinations, attracting 10 million visitors each year. Few, however, would dare to run a marathon on it...

May 2017 saw the 19th running of The Great Wall Marathon, organized by travel company Albatros Adventure Marathons. With 5,164 steps over undulating terrain and an average temperature of 25 degrees, it's hardly your average footrace.

A total of 292 people completed the inaugural event in 1999, while nowadays 2,500 participate across two races, a marathon and half marathon. 2013 saw the race sellout for the first time.

Legs, lungs, feet and hands are all needed to get to the top of some of the climbs. With the men's record standing at three hours, nine minutes, 18 seconds and the women's at three hours, 32 minutes, 12 seconds it takes considerably longer than flat, city marathons.

Competitors, however, would say it's worth it for the spectacular views...

Australian fitness instructor Raquel Holgado competed in the 2017 Great Wall Marathon.

Among the races organized by Albatros is the Big Five Marathon. Founded in 2005, it takes place on the Entabeni Safari Conservancy in South Africa. The reserve is diverse, taking in mountains, plains, bush, wetlands -- and a few animals as well.

There's nothing separating runners from the wildlife, which includes the "Big Five" African game: elephants, rhinos, buffaloes (pictured), lions, and leopards.

The terrain in the savannah is a tricky mix of sand, pebbles, and loose rocks. It's smaller than the Great Wall Marathon, with a maximum capacity of 275 runners.

The views, however, are just as stunning.

Not all the races hosted by Albatros are in hot climates. The Polar Circle Marathon, dubbed the "coolest marathon on earth," sells out within weeks of registration opening.

Biting winds mean temperatures can be as low as -15 degrees on the Greenland Ice Sheet, while the icy surface also makes life hard for the runners.

And if that doesn't sound tough enough, there's also the Polar Bear Challenge -- an additional medal awarded to those who complete both the half and full marathons across the two days within the time limits -- 91 people conquered the challenge in 2016.

The race takes place in October each year.

Held a few weeks before the Polar event is the Petra Desert Marathon in Jordan. Perhaps the hottest of the runs organized by Albatros, it weaves through the ancient city of Petra, taking in sandstone mountains, tombs, caves, and ampitheaters.

Competitors from 2015 stand before the ancient ruins carved out of the red sandstone mountains. Dating back to 4 BC, the city was once home to the Nabataean tribe.

Runners trudge through the arid landscape during the 2015 edition.

The Bagan Temple Marathon winds through more than 2,000 mesmerizing Buddhist temples in Myanmar, on the banks of the Irrawaddy River.

The race starts and finishes at the Htilominlo Temple, which dates back to 1211.

Blue skies, verdant pastures, and red-brick pagodas -- the Bagan Temple marathon is a sight to behold.