The family of the man who donated Tŷ'r Cymry to the Welsh-language community of Caerdydd has called on the trustees to reconsider plans to sell the property.
Tŷ'r Cymry was donated to the city in 1936 by Lewis Williams, a farmer from Bro Morgannwg.
Over the decades it has housed organisations such as Plaid Cymru, Cymdeithas Yr Iaith Gymraeg, and until recently, a Welsh-medium nursery.
A total of fourteen members of Williams' family have written to the trustees.
Cymdeithas yr Iaith Gymraeg has asked local and regional Senedd members what they intend to do to keep the building open.