Local historian Mark Baker has campaigned for Gwyrch Castle to be bought back to its days of glory - a campaign he started when he was 12 years old.
“It is very exciting that the castle will be open for the day and that we have an opportunity for people to learn about its history and what is proposed for the future” he said.
The 19th century castle was once by the Government to house 200 Jewish refugees during the second World War.
Land above the Melon House and Conservatory has now been leased by Gwrych Trust from the owners Castell Developments.
Also leased are the formal gardens which are a designated Site of Special Scientific Interest.
They have Tree Protection Orders for some of the oldest trees in the area.
Gwyrch Castle in Conwy is open to the public tomorrow for the first time since the 1980s.
It's since fallen into disrepair, although planning permission has been obtained to turn it into a luxury hotel.