A 13th Century church, which was dismantled and rebuilt 50 miles away at a museum in Cardiff, has been opened by the Archbishop of Canterbury.
St Teilo's Church has been recreated stone-by-stone over 20 years at the National History Museum, St Fagans.
The church from Pontarddulais near Swansea has been restored to recreate its appearance in 1520.
Copies of a rare series of 16th Century paintings, which were uncovered as it was being dismantled, adorn the walls.
First Minister Rhodri Morgan also attended the ceremony with the archbishop, Dr Rowan Williams.
Mr Morgan believes his great-grandparents married at the church, which was used regularly until 1850 and then occasionally during the summer until 1985.
The archbishop said the restoration was an "amazing achievement"
The first minister said: "I have watched the incredible skills of the restoration team that have reconstructed the building and saved the frescoes.
"This is a stunning addition to the treasure trove of Welsh history contained in St Fagans."
The museum has a number of buildings, representing Wales through the ages, but this was one of its most ambitious projects.
Dr Williams said the church's restoration was an "amazing achievement" and a "real triumph for the country".
The archbishop, who is himself from Swansea, said the restoration was also part of the process of discovering more about Wales' history in the Middle Ages.
"Our history didn't just begin when they discovered coal, our history didn't end when the Romans left.
There's a long period in-between, when we were part of Europe and a big flourishing culture," said the archbishop.
Curator Gerallt Nash said: "Before we actually started the work of dismantling the building, we carried out a rescue operation to uncover what was hidden away beneath layer upon layers of lime wash.
"That was when we found the amazing series of wall paintings here."
The congregation gathered inside the rebuilt church
The discovery influenced the decision to reconstruct the church as it would have looked in the 16th Century - prior to the Reformation.
Specialist craftsmen used traditional methods to build what according to the museum is the UK's first authentic reconstruction of a medieval masonry-built church.
It contains all the elements of a late medieval Catholic church, including a rood screen and a loft, elaborately carved from oak.
Head carpenter Ray Smith said some of the original roof trusses had been saved, but timber had also been sourced from Ruabon near Wrexham.
"I bought all the timbers for the project while they were still standing, so I know where every tree has come from," he said.
The timber for the rood screen - which Mr Smith described as a carved oak screen separating the nave from the chancel - was sourced from Radnorshire.
He researched the history of St Teilo, the patron saint of horses and fruit trees, in order to carve his life story into the screen.
Mr Smith explained the screen had been used in medieval times to keep the congregation out of the chancel - the area where the altar was located.
He said: "It's been a big learning curve for lots of people, because the history involved in recreating a medieval building... is new to most people in this country, in fact, probably around the world."
Those who remember the church in its original location were invited to a service held by their vicar, Reverend John Walters, as part of its opening on the museums' 100-acre site.
The church was moved from its original site in 1985
Rev Walters said: "The church had not been used regularly since 1850, apart from three services a year during the summer months.
"Eventually with slates being stolen from the roof it was decided that something had to be done," he explained.
Rev Walters said entering the church would be strange in two ways for the congregation.
"Most of the people who do remember it there and who remember going to services there in the summer will have quite a surprise, because it's going to be 'dressed up' as it were in its medieval guise."
Mr Smith added: "It's going to be a really big 'wow' factor when the people of Pontarddulais walk in there for the first time."
The church opens to the public on Monday.