Cardigan Castle, the venue for the first National Eisteddfod more than 800 years ago, has been opened to the public for the first time in a generation.
More than 800 people have already flocked to see the previously hidden treasures at one of Wales' most significant - but largely ruined - castles.
It was bought for £500,000 early this year after its elderly owner decided to sell up and move to a residential home.
Ceredigion Council has thrown open the grounds of the castle for a few days before it starts on the long road to renovate the historic buildings in the grounds.
The authority aims to develop the castle as a national cultural centre.
The 12th Century castle has been the focus of a campaign to ensure its future with 3,000 people supporting a petition calling for it to be saved.
"We decided to open the castle up to the public this week after a lot of pressure from local people," said Tim Ball, Ceredigion's head of planning.
"They see the castle as belonging to them and they wanted a chance to look inside the castle walls.
"Parts of the castle are not safe so we decided to conduct guided tours around the grounds so they can see a number of interesting and important features that are there."
The highlight of the tour is the east tower, built in 1244.
There lie two passageways which lead to separate garderobes - medieval toilets.
The passages have stone steps and a vault with an unusual design, believed to be the only ones in Britain,
This 1244 passage is thought to be unique in the UK
The North Tower, also built in 1244, may be the earliest British example of an angle-spur buttressed tower.
The front range of the house inside the castle walls, Castle Green House, was built in 1827 and has a timber porch trellis which has never been altered or repaired.
In the grounds of the town centre castle stands a whale bone imported from Canada in the 1870s when Cardigan was still one of Wales' major ports.
It is the first time the castle has been open to the public in 15 years.
Local historian and town councillor Glen Johnson said excavations should reveal more of the castle's secrets.
"The grounds have been landscaped in 1713 and the early 1800s so some digging will have to be done to reveal whatever was buried there before," he said.
"It would be very exciting if some trace of Lord Rhys' court hall where the first eisteddfod was held were found," he added.
Cardigan Castle will be open to the public on Saturday 15 November between 1000GMT and 1500GMT.