Travelling Photographers

Ricalton Stereoscope

Look carefully at the pair of images. They are in negative. If you turn them into a positive image you can see that this photograph that I have found in the Smithsonian archives was taken in 1908.
Can you locate the building and the city?
What were these pairs of photographs known as and how were they viewed?
I will be looking forward to you answers.
Kind Regards,
Dr Mackey at the Smithsonian