The buried St Piran’s Oratory near Perranporth is set to be excavated by experts, after permission was finally given.
The medieval site near Perranporth sits inside a concrete bunker, after being buried over 30 years ago.
The archaeological services of Cornwall Council willexcavate the oratory, evaluate the integrity of the structure and formulate how to go about preservation work.
A spokesman for the St Piran's Trust said: "We are delighted to announce that after 14 years of campaigning, the St Piran Trust has finally secured permission to uncover St Piran's Oratory.
"Excavation is scheduled to begin in February/March (weather dependent) and volunteers are encouraged to take part.
"Finally, Cornwall's premier cultural site is receiving the attention it has so long deserved."
The Oratory – believed to be the oldest four-walled Christian edifice on mainland Britain – is a scheduled ancient monument and listed building, and was built by the Cornish saint, St Piran, in the fifth or sixth centuries, according to tradition.
The Trust launched the campaign to excavate the Oratory after it was buried under sand dunes for its own protection in 1980, on Department of the Environment advice.
Since then, expert opinion has shifted and it is now believed its burial has endangered the edifice, resulting in English Heritage’s decision to place it “at risk” in 2011.