Watch a report from ITV News Anglia's Rob Setchell.
Multi-million pound restoration work at Norwich Castle has unearthed some of the secrets of its past.
The project aims to return the Norman keep to its former glory - rebuilding its five medieval floors so that visitors can experience a full royal palace, from basement to battlement.
Construction work started last year but the pandemic - and the need to move carefully around the historic features of the ancient monument - means progress has been slow.
It's now thought the project won't be completed until mid 2023 and costs have also crept up to around £16m. Most of that money has come from the Heritage Lottery Fund.
Contractors have been working around historic graffiti on the walls of former prison cells and excavations also revealed hidden history, including some of the earliest defences built just after the Norman Conquest.
Robin Hanley, Assistant Head of Norfolk Museums Service, said: "We did at one point discover an unknown stairway that led down to the workings of the treadmill that prisoners would have worked as part of their sentence.
"Other excavations have given a hint at the sort of life people were living. Feasting evidence - with even discoveries of porpoise bones - giving a sense of the rich diet that might occasionally have been enjoyed by royal visitors such as Henry I."
The Norwich Castle scheme is one of the biggest heritage projects currently taking place in the country. Matt Bidewell, Senior Project Manager at Morgan Sindall, said it was an honour to be working on it."It's a once in a lifetime, once in a career, project for me," he said.
"I have historic memories of the building. I came here as a child and saw the mummified cat and the Egyptian gallery. I remember coming round and my mum being put on the ducking stool in the dungeons.
"I'll be able to bring my children into this building. It's more than just bricks and mortar. This is a story, an asset not just for Norfolk but for the entire country."