Remnants of an ironworks which played a vital part in York's 19th century economy go on show on Saturday.
Parts of the Walker Iron Foundry were unearthed by archaeologists working on a site on Walmgate in the city centre.
The site is being opened between 11am and 3pm so visitors can see the latest discoveries.
A spokesman for York Archaeological Trust said the excavation would reveal much about the technology of iron founding at a crucial time.
Gas lamps
Born in 1801, John Walker became an apprentice ironmonger in York in 1815 before going on to set up his own business in 1837.
The firm started as a local supplier, making the first gas lamps and railings for St Leonard's Place.
Walkers' fortunes blossomed in the 1840s, when the firm made the gates to Kew Gardens in London and John Walker became iron founder to Queen Victoria.
The company's most famous commission, the gates and railings for the British Museum, came in 1850.
Industrial excavation
The first factory, at Dixon's Yard, was sold for £1,000 in 1856 when the firm moved to the nearby Victoria Foundry.
York Archaeological Trust fieldwork director Patrick Ottaway said: "This is the first major excavation of an historic industrial site in York.
"I believe it will tell us an enormous amount about the technology of iron founding in a crucial period of its development.
"This site also has special significance for the city because of the Walker connection," he added.