Some of the earliest photographs of old Beijing are set to go up for sale in London on May 15. Shot more than 150 years ago, the 18 pictures reveal a Chinese capital long since gone. At the time, they were the first images of China most Europeans had ever seen. When they come up for auction at Sotheby's, it's believed bidders from around the world -- and in particular China -- will value the pictures at around half a million dollars.

The price tag on these photographs a reflection of their unique nature.

Shot by the British-Italian photographer Felice Beato they're extraordinary on a number of levels.

Photography was in its very infancy when incredibly in 1860 Beato took his equipment on the road to snapping these unparalleled images.

Beato's technical excellence demonstrated here by the world's first panoramic shot of the imperial splendour of China's ancient capital.

Among Beato's portfolio images from 150 years ago that are unique … of a China changed forever by time.

These images were shot at a time of traumatic change in China. Beato came to the country as a 28 year-old war photographer, along with invading Anglo-French forces during the Second Opium War in 1856-1860.

One photograph on the auction catalogue's cover page is the only surviving record of the Summer Palace, pictured shortly before it was torched by British and French troops.

With private collectors on the phone from China among the bidders, there's every likelihood these pictures will join a growing global tide of Chinese antiquity returning to its country of origin. And that say experts here at Sotheby's is exactly the way it should be.