A skeleton found in Lincoln Castle could belong to a Saxon king or bishop, according to archaeologists.
The skeleton was in a stone sarcophagus believed to date from about AD900.
Although the sarcophagus has not yet been opened, an endoscopy revealed the remains were buried alongside other objects - possibly gold.
Programme manager Mary Powell, of Lincoln Castle Revealed, said: "We think it's somebody terribly important - possibly a bishop or a Saxon king."
The sarcophagus is buried approximately 3m (9ft) underground.
"At the moment, we can see the side of the coffin, but not the lid," Ms Powell added.
"It's going to be incredibly challenging to get it out, so we are being very careful.
"There is a danger it could disintegrate because of the change in environmental conditions.
"When we do finally lift the lid, the plan is to record what's inside immediately, in case it starts to disintegrate."
She hoped there would be carving on the lid which might reveal the identity of the skeleton.
"We know so little about the Saxon period and Saxon coffins are very rare," she said.
"We are all excited about lifting the lid and seeing who is in there and what is buried with him."
The limestone sarcophagus was found alongside a Saxon church with eight other skeletons, all buried in wooden coffins, one in a woollen shroud.
The team has been carrying out DNA examinations of the eight skeletons. They also hope to do a digital reconstruction of the skeleton in the sarcophagus.
Ms Powell said archaeologists were looking into a possible connection with an 8th Century king of Lindsey named Blaecca.
The dig also revealed two Roman town houses. A skeleton of a baby was buried nearby.
The £19.9m Lincoln Castle Revealed project is aimed at creating a visitor attraction at the venue, including an underground vault in which to display Lincoln's Magna Carta.
Many of the finds will go on display when the project is completed in 2015.
"Nobody really expected to discover as much as we have," said Ms Powell. "We don't think one room is going to be big enough. We may need to find a bit of extra space."