These newly unearthed pictures give a rare glimpse into Sheffield's smog-filled industrial past.
The images are from a collection believed to span from the 1930s to the 1950s.
Some of the pictures are said to illustrate the construction of the original Co-operative store on Castle Hill and Castle Market between 1928 and 1930.
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The pictures have been shared by Dr David Clarke. a former Sheffield Star journalist and now a lecturer at Sheffield Hallam University, who had been showed them by a woman called Wanda Corbey.
Ms Corbey explained that they had been found in family archives and had belonged to her late father-in-law Jack Corbey, who found time to take the snaps while working as an electrician at the site.
During building work it is believed they discovered remains of the former medieval Sheffield Castle, which was destroyed at the end of a Civil War siege in the 17th century.
The unearthing of the pictures is also timely as excavation work by archaeologists got under way at the Castlegate site this week in a bid to discover more about both the castle and the site's later industrial past.
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Dr Clarke described the images as "absolutely stunning" and added: "They show parts of industrial Sheffield covered in 1930s smog and what may be parts of the old Castle ruins.
"The clocktower of the Old Town Hall on Waingate can be clearly seen on two of the rooftop images, as can buses or trams on Lady's Bridge with Tennants brewery and the chimneys lining the River Don in the direction of Kelham Island below.
"We are hoping readers might be able to identify some of the workmen on the photographs."
Just a decade after opening, the flagship Co-operative store was badly damaged in the Blitz in 1940.
A new department store was opened in nearly Castle House in the early 1960s.
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The five-storey Grade II listed building has been mainly empty since the Co-op closed the store in 2008.
Ambitious plans have recently been revealed to open a food hall inside part of it and for other floors to be used as a hub for digital businesses.
Castle Market was demolished in 2016 which paved the way for the archaeological dig started this week.
Initial plans are being drawn up for the future of the old market site, which is set to include more green areas as well as pedestrianised zones.
*Do you recognise any of the workmen in the pictures? Email firstname.lastname@example.org