Some of the world's attractions take a bit of extra effort to see. Ancient monuments, historic cathedrals and sacred temples were not built with accessibility in mind. Pure Gym has put together a ranking of the world's most physically demanding landmarks.

They used factors including the number of steps, the elevation change during the ascent of the landmark, and the average temperature of the location to produce rankings. "Many people will know the feeling of climbing hundreds of stairs and reaching the top of a viewpoint feeling like you've just completed a gym class, so we wanted to take a closer look and find out which landmarks are the most physically demanding overall," the company said . Here's the top 15 list.

 Heaven's Gate or Tianmen Mountain in China is a Tianmen Mountain National Park, Zhangjiajie, in the northwestern part of Hunan Province, It has a 999 step entrance known as "the Stairway to Heaven". READ MORE: Here are all the best places to stay in Phuket, depending on what vibe you're after It does have a cable car part of the way up, but you have to walk the final ascent. The World Heritage listed Cathedral of Saint Mary of the See in the Spanish city of Seville was finished in 1519.

There are 700 steps to reach the top of the tower, making it a bit of a workout. That incredible staircase clinging to the side of Guatapé Rock has 740 steps. But it's the steepness which helped to put it at number 13 on the list.

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