BBC News presenter Huw Edwards is to call for more to be done to "champion" Welsh chapels and their contribution to cultural and historical life.
In a lecture at Swansea University, he said the buildings must be better protected by public bodies behind "some of the worst cultural damage".
He accused cultural and heritage chiefs of being "castle, cathedral and country house obsessives".
The Welsh government said chapels were a vital part of Wales' history.
The Royal Commission on the Ancient and Historical Monuments of Wales (RCAHMW) has put together a register of more than 6,600 19th and 20th Century chapels.
More than half have shut with the others closing at the rate of one a week.
Mr Edwards is already leading a campaign to save Jewin Presbyterian Church, the oldest Welsh chapel in London, where he is a worshipper.
Mr Edwards's lecture called for the role of chapels in Welsh culture, history, and society to be recognised and rehabilitated.
He said: "Chapels can be championed in several meaningful ways.
"Their story can be retold and presented to a new audience, their place in the education curriculum must be revised, and the fabric of chapel buildings must be protected in a much more rigorous way."
He said the Welsh government, its heritage arm Cadw, and local conservation bodies and local authorities "who have often sanctioned some of the worst cultural damage" each had roles to play.
"It is already too late for some of our best chapel buildings," Mr Edwards said.
"Future generations will wonder what on earth we were doing. But it is still possible to save some for the benefit of their local communities."
A spokesperson for the Welsh government said: "Churches and chapels are a vital part of the country's history and culture and central to helping our understanding of the past.
"This year, grants of up to £375,000 in total have been awarded by Cadw to 13 projects to repair and restore historic places of worship across Wales.
"Cadw is also developing new guidance to support the care, conservation and sensitive development of places of worship.
"Cadw recognises that repair and restoration costs of chapels can sometimes be costly but a high standard of work is an investment which helps to safeguard the historic character of chapels for the future."
Mr Edwards is a trustee of the Welsh Religious Buildings Trust, a committee member of Capel - the chapels heritage society - and author of The Chapels of Wales.
The event was organised by the Learned Society of Wales.