An exhibition titled The Great Wall - Photographs Then and Now at London's Charing Cross Library features an iconic photo by William Edgar Geil, in 1908, showing two Chinese men sitting on the Great Wall in Qing Dynasty (1644-1911) clothes and long hair in braids.

Scholars have long hailed the Great Wall of China as unique, but a new photo exhibition on the spectacular Chinese fortification shows it has a little sister - Britain's Hadrian's Wall.

Currently exhibiting at London's iconic Charing Cross Library is a collection of about 50 photographs on the two walls, taken by archaeologists, scholars and travelers from both China and the West over the past 140 years.

Less known than its counterpart, Hadrian's Wall was built by the Romans in Northern England in AD 122, stretching 120 km between Solway Firth and Wallsend suburb.

Both built initially as defense fortifications, the Great Wall and Hadrian's Wall were both inscribed as UNESCO world heritage sites in 1987.

To celebrate their 25 years of friendship, Phoenix Publishing & Media Group and the Hadrian Wall Trust have organized a photo exhibition, titled The Great Wall - Photographs Then and Now.

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Chen Haiyan, chairman of PPMG, also signed a memorandum of understanding with Linda Tuttiett, chief executive of Hadrian's Wall Trust in July, to cooperate in academic studies and tourism development of the two walls.

"Working together, we hope to raise awareness of both sites among new audiences across the world. In turn, that should help their potential to contribute to local communities through sustainable tourism development," Tuttiett says.

Tuttiett's words are echoed by Chen, who adds that collaboration can "promote historical and cultural exchanges between China and the UK".

The photographs for the Great Wall are selected from Remembrance of the Great Wall, a recently published book by Zhang Baotian, who led a group of volunteers to search and collect old photographs of the Great Wall as well as taking modern images from the old locations between 2001 and 2011.

Among their collections are photos dating back to the 1880s. The new camera technology attracted many pioneering photographers including George Ernest Morrison from Britain and William Edgar Geil from the United States, whose works have become part of Zhang's collection.

The oldest picture was taken by British photographer Felice Beato, in 1860, who shot the Great Wall from the ground level up. Another iconic photo, by William Edgar Geil in 1908, shows two Chinese men sitting on the Great Wall in Qing Dynasty (1644-1911) clothes and long hair in braids.

The juxtaposition of the historical and new photographs strikingly demonstrates time's toll on the great fortification, as the newer photographs show parts of the same structure weathered and eroded.

The photographs of the Great Wall have already appeared in three exhibitions earlier this year - once in Beijing and twice in Jiangsu province.

Wanting to showcase the photos to a global audience, PPMG contacted Hadrian's Wall Trust two months ago.

The Hadrian's Wall Trust agreed to help immediately and proposed to supply photographs of Hadrian's Wall for the exhibition. These photos feature Housesteads Crags and Castle Nick, landmark features along the Hadrian's Wall Path.

An English-language version of Remembrance of the Great Wall will soon be published by New Classic Press, which bought the English translation rights of the book from PPMG.

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