These rare photographs taken more than 150 years ago are thought to be among the first ever pictures taken of China.
Showing Beijing in the days before sky-scrapers when it was still known as Peking, the photographs were taken by Anglo-Italian photographer Felice Beato and include the first ever panorama of the city.
The collection also includes the only known photograph of the old Imperial Summer Palace before it was destroyed by fire by British troops in 1860.
This is the left half of the panoramic image, thought to be the first ever such shot taken of Peking, as Beijing was then called, by Anglo-Irish photographer Felice Beato
This is the right half of the panoramic image, taken in 1860 when the gleaming skyscrapers the inhabitants of today's Beijing were still more than a century away
This panorama, seen in its entirety, is 5ft 5in wide and 8in tall and was taken from Peking's South Gate looking towards the Forbidden City
The set of 18 original albumen photographs were taken by Mr Beato, regarded as one of the first ever photojournalists, while he was embedded with the British Army in 1860.
Mr Beato had joined up with the army in India in 1857 to photograph the uprising in the country at the time before travelling on to China. He captured daily life with the troops, as well as landscapes and historical buildings around the country.
Thought to be the first ever photographer to visit Beijing, Mr Beato took a series of six shots from the South Gate looking towards the Forbidden City which became the first ever panorama of the city.
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The resulting photograph, printed on fine photographic paper, is 5ft 5ins wide and 8ins tall.
Mr Beato also photographed the old Imperial Summer Palace, part of a private estate owned by the Emperor of China, just days before it was torched by the British and French armies.
Other photos in the collection feature Pehtang, North Taku Fort, tombs near Peking and the Imperial Winter Palace. Mr Beato's images of the historical buildings and landmarks are among the only ones in existence.
The collection includes a picture of the old Imperial Summer Palace taken just before it was burnt down, left, and one of the gateway to the Great Llama Temple, right
On the left is a tomb of an Empress of China in Peking, while the picture on the right shows the left bastion of the captured South Taku Fort in Peh-Tang
He sold them to an army lieutenant while in China before returning to Britain where he sold 400 pictures to a commercial photographer who reprinted them.
The collection is tipped to fetch £200,000 when it is auctioned by Sotheby's on behalf of a private collector in London on May 14.
Richard Fattorini, director of books and manuscripts at the auction house, said: 'These photographs are of huge historical significance - they are among the first photos ever taken of Beijing and include the first ever panorama taken of the city.
'These photographs provide a fascinating insight into a lost time before the forests of skyscrapers that dominate China's landscape today.
'Beato had very cleverly got himself entrenched with the British Army and had joined them in India in the mid-1850s. He then travelled to China with the Army and documented day-to-day life, almost like a newspaper photographer would have done. He was probably the first photographer ever to visit Beijing.
'He was a specialist in taking panoramic photographs, and one day he got up onto a wall overlooking Beijing towards the Forbidden City and took an incredible panorama made up of six separate shots.
This image shows the captured Taku Fort at the mouth of the Pei-ho river, taken by Felice Beato in China during the summer of 1860
'At the time it would have been incredibly difficult to do, with each shot lined up perfectly. It was the first ever panorama taken of the city.
'The collection also includes the only photograph in existence of the Imperial Summer Palace just days before it was torched by British troops.'
While still in China, Beato sold his photos on to Lieutenant Edward Courtney who marked each one with a caption. The original images were passed down through Courtney's family before ending up in a private collection.
On his return to Britain, Beato also sold 400 images to Henry Hering, a commercial photographer from London, who reprinted them and sold them at £20 for 69 photos.
Mr Fattorini added: 'The photographs are in remarkable condition given they are 150 years old.'In the last year or so, early photos of China have become extremely valuable as collectors recognise their significance, and these are among the finest examples.'