Dyffryn House and Gardens reopen to the public today under the management of the National Trust.
Vale of Glamorgan Council will continue to own the property, while granting the Trust a 50-year lease.
"Growing and shaping a glorious garden is a long-term project" said Justin Albert, Director of the National Trust in Wales.
"The passion that has gone into creating Dyffryn Gardens over the years - from volunteers, staff and supporters - cannot be taken for granted. And we want everyone to join with us in harnessing that passion for a new stage of Dyffryn's journey."
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Local authorities said the move is necessary to "avert the growing number of deaths and increasing harm linked to psychoactive substances".
Sunny and bright spells for most of us this afternoon, feeling pleasantly warm.
North Wales Fire and Rescue Service say incidents of deliberate fires are more common during the school holidays.