The city of St Davids has been an important site of European pilgrimage since the 7th century AD
A 15-year project at The Bishop's Palace, St Davids, has been nominated for a prestigious conservation prize.
The project has been short-listed for one of six Grand Prix awards by Europa Nostra, the Pan-European Federation of Cultural Heritage.
It is up against 29 other similar conservation works from across Europe for the awards.
The winners will be announced in Istanbul in June as outstanding examples of heritage protection.
Only one other UK project, St Martin in the Fields, London, is competing alongside St Davids Bishop's Palace in the same category.
In the judges' view the Bishop's Palace has been beautifully and imaginatively restored by Cadw, the Welsh Assembly Government's historic environment service, and its works arm Cadwraeth Cymru, with outstanding presentation material to enlighten future visitors.
The conservation work itself involved consolidation of the entire building and its architectural features and replacement of missing floors in order to make the complete circuit of the first floor accessible.
Specific work included replacement of decayed stone, selective repair and replacement of architectural mouldings, and 'soft mortar' repair of statues.
The work has enhanced the historic character of the cathedral precinct
The city of St Davids has been an important site of European pilgrimage since the 7th century AD.
Such was its importance that in the 12th century a papal privilege granted that two pilgrimages to St Davids were equal to one to Rome.
The Bishop's Palace sits within the cathedral precinct in a prominent position adjacent to and facing the cathedral.
A major outcome of the conservation work on the exterior of the palace has been to enhance the historic character of the wider cathedral precinct, which is visited by in excess of 300,000 people each year.
The palace was built by Henry de Gower, Bishop of St Davids from 1328 until 1347.
It enjoyed three-and-a-half centuries of occupation between its construction and eventual abandonment during the late 17th century, after which it fell into disrepair and subsequent ruin.
In 1932 the Representative Body of the Church in Wales placed the ruined palace into the care of the state.
The palace represents the vision of one man, Bishop Henry de Gower
Today, it is managed by Cadw, the historic environment division of the Welsh Assembly Government.
By the early 1990s, the condition of some areas of the palace was causing major concern.
The buildings were constructed of a mixture of local stones; some of the Pre-Cambrian volcanic rock was eroding in the wind and rain at an alarming rate (in places up to 10cm back from where it had been in the 1930s); patches of walling had become so thin that some structural collapse was imminent.
Dr Kate Roberts, Cadw's Inspector of Ancient Monuments, said: "The primary purpose of this challenging project was to preserve the Bishop's Palace, which is the most complete surviving secular building of the second quarter of the 14th century in the United Kingdom.
"Its ruins represent the vision of one man, Bishop Henry de Gower, and the skills of the master craftsmen he employed.
"To have this work recognised as being some of the best conservation work undertaken in Europe is a great honour and while it has been a very long project we are extremely pleased with the final outcome."
The aim of the Europa Nostra awards is to promote high standards and high quality skills in conservation practice and to stimulate the trans-border exchanges in the area of heritage.
By spreading the power of example the awards also aim to encourage further efforts and projects related to heritage throughout Europe.