Archaeological digs have been going on at Cardigan Castle for the past two years - but only five percent of ground has been investigated.
"I think this is incredible and throws up very exciting prospects," castle archaeologist Nigel Page told a talk at the Guildhall this week.
Finds have ranged from eagle bones and medieval pottery to Victorian clay pipes and a Civil War earthenware dish.
"It is a fascinating site with many more secrets left to uncover," said Mr Page.
Two medieval arrowheads were also unearthed at the site.
"These are the only signs we have found of the castle as a military site - the only other one was a Naafi mug from the 1940s!" said Mr Page.
Some of the most exciting finds were solid stone medieval structures that would have been capable of supporting buildings that were several storeys high.
The digs have enabled archaeologists to map out a rough medieval outline of castle buildings.
"What is interesting is that the shape of the house was dictated by the medieval walls - even though those buildings are 500 years apart," said Mr Page.
The hallway of the Georgian house matches the exact width of a medieval archway discovered beneath the floor.
But what of Lord Rhys's great hall which housed the first eisteddfod back in 1176. Does it lie beneath the house?
"As a key building it would be in the right place but I would be reluctant to say," said Mr Page.
But castle expert Father Cunnane begs to differ - he thinks the hall would have been situated between the two castle towers overlooking the river.
"I think that's the place that needs looking at," he said.