Castlegate: Archaeologists uncover secret 19th century steelworks furnace, hidden near Sheffield city centre

Hidden secrets about Sheffield’s industrial past have been uncovered by experts - with a secret steelworks furnace uncovered in the city centre.

Archaeologists excavating the site of Sheffield Castle say they have discovered previously unknown remains of the steelworks, dating back over a century.

No documents had existed to give any clues that the former works furnace had been at the site, which was later hidden by developments such as the Castle Market.

A team of archaeologists from Wessex Archaeology uncovered the previously unknown evidence of Sheffield’s industrial heritage while digging at the former castle site, which is part of Sheffield City Council’s Castlegate regeneration project.

Overseen by construction engineering specialists, Keltbray, it will transform the derelict site into a new park. The green space overlooking the River Sheaf, due to open in 2026, will display remains of the medieval castle.

During the first few weeks of the excavation, the team has been exploring 18th/19th-century remains, revealing parts of a possible slaughterhouse and the Castle Hill Steelworks that occupied the site in the 19th century.

The remains of one of the steelworks’ crucible furnaces, not recorded on contemporary maps, can now be explored in an 3D interactive model (click to view model).

The cellar of the crucible furnace structure, with its signature complex of brick bays, survived up to ground floor level in places. The furnace cellar that was reached via a set of curving stairs, featured a set of ‘rake-out’ pits that sat below the furnace and had been demolished and backfilled with ash and brick rubble.

As well as gaining an understanding of the layout and workings of the furnace - used to refine blister steel into higher quality crucible steel - the team uncovered several clues that shine a spotlight on the people who operated the furnace.

Reaching temperatures of 1200C., the firing process was hot work and hard going. On the walls of the crucible cellar the letter ‘H’ was scratched into the brickwork. It is not known whether this was the initial of someone who toiled in the cellar day in and day out.

The team also uncovered someone’s secret hiding place. The hole in the wall had been dug out and another brick was placed in it to conceal it. Archaeologists say nothing was found in the hole, but the features were helping to paint a picture of the people who powered the steel industry and fuelled the growth of the city.

Ashley Tuck, the archaeologist leading the dig on behalf of Wessex Archaeology, said: “These remnants of Sheffield’s industrial past not only remind us of the role steelworking played in the growth and identity of this city, but they also encourage us to consider the people behind it who would, by modern standards at least, have worked in an unpleasant and challenging environment.”

Louise Pavitt, managing director for highways and local government at Keltbray, said: “Keltbray is excited to support Sheffield City Council on this historic regeneration project that will permanently reveal sections of the old castle for the first time in over four centuries.

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“We’re excited that local people will be able to attend and learn more about the work that our industry does around cultural heritage.”

Throughout April community members have been participating in the excavation. Bookings are now open for tours and opportunities to excavate the site this May.

One participant said, said: “I’m really enjoying it, it’s a wonderful opportunity for a Sheffield person to be able to take part in this historic archaeological dig. I’ve felt this morning ... when I was getting up that I was going to step back into history and it just feels exciting and adventurous to actually be part of what’s going on and to be able to say to people in years to come ‘I stood on those ruins, on those stones’ and it was just great fun.”