Now work is to begin on the restoration of the Kilallan Kirk, which dates back over 1000 years but which was last used more than 240 years ago.
The kirk, the origins of which are believed to date back to the 10th or 11th century, is considered one of the nation's most important Pre-Reformation church sites, representing an example of the continuous development of a medieval parish church and churchyard up to the 18th century.
Tucked away in a secluded and wooded area in rural Renfrewshire between Kilmacolm and Houston, the old kirk has for many years been a roofless structure, made up of four low walls, almost completely intact.
But over the last decade the kirk, which received Scheduled Ancient Monument status in 2003, has begun to show signs of deterioration, with obvious bulging and cracking of the masonry walls.
Areas of ironwork have rusted away and are missing, and the cement cope protecting the top of the wall has also failed, letting water in and allowing plants to grow between the stones.
To deal with the problems the trustees given care of Kilallan in 2005 are to start organising the careful repair of the building using grants and donations of £210,000 from a number of bodies.
They include Historic Scotland, the Heritage Lottery Fund, rural development group Renfrewshire Leader, Elderslie Estates, the British Airports Authority, the Dalrymple Donaldson Trust and the Mackichan Trust.
William Lindsay of property consultants CKD Galbraith is the on-site project manager and will be overseeing all of the preservation works. Although he has been involved in many listed building projects this is his first scheduled ancient monument.
He said: "It's already really exciting as many similar projects can fall away due to the red tape involved, but with the right expertise and generous support we've got around that.
"It's really about preserving what's here, keeping the character of the kirk. It's not about making Kilallan look new or an interpretation. As with all archaeological sites there may be a few surprises thrown up but we've prepared well."
The preservation work, starting on September 30, is expected to take around five months.
It will include the consolidation and repair of the stone walls, the refurbishment and decoration of the cast-iron railings, the installation of some interpretive panels and a small setting-down point for visitors.
The wider project includes the delivery of an extensive community activity programme aimed at breathing life into the ancient monument, with the Trust putting together a volunteer and training programme focused on local people learning new skills and getting as many members of the community as possible participating in the project.
Kilallan Kirk is dedicated to St Fillan, the Scottish saint with Irish origins who is believed to come from Cluain Moescna, Meath, Ireland. It was one of seven churches in Renfrewshire gifted to Paisley Abbey by Walter the High Steward in 1169.
The church was last used in 1771 when the parishes of Houston and Kilallan merged. The graveyard was in use until 1856, and the manse is said to be one of the oldest inhabited houses in Renfrewshire.
Kilallan Kirk is linked to the infamous Paisley Witches, also known as the Bargarran Witches, who were tried in Paisley in 1697.
A plaque remains on an external wall of the kirk in commemoration of the Reverend James Hutchison.
He helped have the seven accused found guilty and hanged, and his family are buried in Kilallan graveyard.