The Chicago star has handed cash to members of a trust to help them buy farmland believed to be the site of a lost palace once home to the last princes of Wales before the country was conquered by English King Edward I in the 13th century.
Members of the Garth Celyn Trust plan to erect a public monument to the princes on the land near Bangor, and they are pleased to have Zeta-Jones' support.
Trustee Paul Martin Remfry says, ""The home of the Welsh princes of Wales has been ignored for far too long. The trustees are delighted that Catherine Zeta-Jones is taking a personal interest in the work of the trust. Her involvement will undoubtedly help to raise the profile of this Welsh project internationally.
""The historical and archaeological evidence is overwhelming and we want to ensure its guaranteed preservation for the benefit of present and future generations.""